Once more the topic of PDO in football has risen to be debated among the analytics Twitterati; opinion has been kicking around for a few days and the Analytics FC podcast chatted around the topic too. I got a mention as someone who uses PDO in analysis, which amused me as generally, but not exclusively, I consciously try to avoid using it in writing.
No matter, i'm well aware of the issues with the metric but slightly mystified as to the strength of anti-opinion it still generates. Nobody is claiming PDO as a top line metric, as James Grayson has shown regularly, it does not habitually repeat and regresses over time. What it does do is give a useful one hit overview of a metrics that a team has little to no functional control over. Precisely because it oscillates around a fixed point gives it a degree of simple understanding.
As I write West Ham have a PDO of 122 which is high and incredibly unlikely to sustain. Similarly Southampton and Liverpool have PDOs at 78 and 81, which are equally low and equally unlikely to sustain. What does this tell us? Via one number we have an instant method of cutting through the overlying narrative that a team is good or bad; we can see whether a team is running hot or cold. For this reason, some of the strengths of the metric as an informer lie around its ability to define reasonably short periods of time.
At its extremes we find teams that are interesting and it offers us a route in for for further analysis. Having highlighted West Ham via their extreme PDO, I can then quickly zoom in on the factors that are contributing. Their save percentage is slightly high, but not too extreme (74%) but the rate in which their on target shots are being converted is huge (49%) and simply will not continue at that level long term. Then we can look at shot levels and be less than impressed, or their wider all shot conversion and ponder that either their finishing talent is akin to Barcelona or it's a freak run.
Liverpool are dying at both ends, Southampton's problems are all in the save percentage. We spot this with a one hit metric, then we look deeper for further issues. Are these teams spending a lot of time in deficit or ahead? Are they crippled by injuries to key players? What is going on?
Nobody conducts in depth analysis using PDO alone, like any metric, in isolation it has limited use. Its components are far more useful as part of a chain of metrics that inform on different aspects of a team's qualities. Chief among the chain will likely be a version of a shot metric be it simple or an iteration of expected goals and more and more we seem to be moving towards ideas around zones.
A by-product of all this is as complexity increases and standardisation remains tantalisingly out of reach, there is still value in metrics derived from actual events. With reticence still prominent in many aspects of football-- from clubs to media to fans-- there is a small duty among analytics proponents to maintain a degree of accessibility and understanding. With many people focusing on a move towards club work, it is worth noting that recommendations for the forthcoming Optapro forum have placed an emphasis on relevance and applicability and we've certainly not reached a point where rejection of simply derived metrics benefits the whole.
And how do you replace a simple concept?
A kind of plus-minus expected goal figure is hindered by the aforementioned issue of non-standardisation and complexity of derivation and even in usage largely highlights the very same teams as a basic PDO calculation. Anyway the factors involved here are not fixed measurements of a team's quality. Like a recipe, relevant ingredients come in different quantities yet combined can create the right mix. For too long too much focus has been put on issues with this metric, be it the mysterious name or non-intuitive meshing of non-related aspects, and missed its simple strength; as a simple temperature gauge for a team's performance.
That's all it really does, and all it needs to.
Time to move on.
Wednesday, 7 October 2015
Friday, 24 April 2015
Analytics for the People
Richard Whittall has recently written an excellent column for 21st Club in which he explores the gap between analytics
and its functional implementation with football clubs. He
finishes up with this:
The current field in football analytics is very good at many things, but not so good sometimes in identifying specific problems for which analysts may provide a partial or whole solution. Work on the latter will help further bridge the gap between analyst and club. Sometimes, it’s important for analysts to step out of R and Tableau and start to breakdown if and how clubs can actually move the needle on some of these predictive metrics. Otherwise, they are like doctors who are only able to offer a diagnosis, but not a cure.
Wise words and certainly advice that should be heeded if you are one of the many people in the market offering analytic solutions for football clubs. With such work being necessarily proprietary and the retention of a competitive edge encouraging secrecy from within clubs, it is not always obvious how analytically switched on the industry is. Leading data providers such as Opta and Prozone occasionally offer a window into the products they offer to clubs, in particular recent Prozone videos from Hector Ruiz and Paul Power showed great skill and clarity alongside the benefits and economies of scale afforded by full data access and a dedicated and skilful workforce. One presumes that by this point most clubs will have at least a small analytics department and probably a lot more. Whether such a department is fully integrated with coaching or the first team will likely vary on a club to club basis, but the point remains: analytics does not exist in a bubble, it is in place, there are professional companies that can offer a full package and access to the market from the outside is difficult. Plenty of people want to work in football and whilst smart in principle, co-opting a few models from other industries and creating a brand is unlikely to improve on what is already available. But, and I feel this is important, a desire to work in football is not the only reason people are interested in or learning about analytics.
Indeed, none of this has stopped a vibrant online amateur community from sprouting up in recent years. The advent of data sites such as Whoscored and Squawka has offered easy access to data at a level that far exceeds what was available prior. Now, anyone with curiosity can collate data from numerous competitions at a player and team level and play with it. It can be analysed and truths, both whole or partial, can be uncovered. These truths have a variable application. For some, with good technical skills, predictive modelling can inform betting, for others fantasy football. I choose to tell stories about what I've deduced and i've sunk many hundreds of hours into it because I find it interesting and intellectually rewarding. As with any subject, there is a learning curve that never ends, not everything I do hits the mark and there are few short cuts to knowledge, but as others who've done this before me have noted, you do it because it's fun.
The current situation in analytics has created different viewpoints. Firstly there is a great drive for predictability, repeatability and application. These are entirely logical and commendable aims, but the arms race to maximise these effects has lead to a shroud being laid over the details involved. In particular, and with one notable exception from Michael Caley, the multiple black box Expected Goals models and advanced derivatives regularly cited have obfuscated analysis due to their non-standardisation. This is not criticism of any specific model, many hours of hard work and theoretical analysis will have gone into each by people with far more advanced skills than myself and those with such access have doubtless found multiple utilities for insight gained. My concerns lie around accessibility and interpretation and this is where I feel some parts of the analytics community have missed the point.
Barriers to entry may have reduced over time, but barriers to understanding have not. There is no such thing as an "Expected Goal", it is entirely theoretical. A layman interested in football statistics may not yet understand the value of a shot or a shot on target yet he is quickly encountering hypothetical versions of the things he does understand: goals. That is a tough sell. Shot counts are real and easily understandable, they aren't "outdated" metrics, they are the building blocks of all that comes after and if the analytics community has any interest in popularising it's method of thinking and transcending a niche corner of football, the stories told by our fundamental metrics are intrinsic.
And there are many stories to be told. Variance in league seasons of 34 to 46 games is huge. Half and whole seasons can go by where the measurable statistical reality of a team is skewed vastly in either direction. Liverpool's huge overachievement of 2013-14 followed by an almost inevitable regression this season, just one obvious case. It isn't just the board that need to understand the wider implication of such matters, the fans can benefit too. Interpretations may differ but we can pull apart possible reasons in the numbers and disseminate the knowledge. Oh for a day where the average pre-game conversation involves an understanding that a team's save percentage has been unsustainably high or a striker gets cheers rather than murmurs or abuse because fans understand he's been unfortunate rather than inept.
It's probably a long way off but as each year passes, we collect more data and we can test more outcomes. Our knowledge can grow and with it our expertise and ability to inform. It is important to encourage people new to the movement and support their effort. We may strive for professionalism but we all start as amateurs. Guide rather than chastise and realise that the more people that are interested in football statistics and analytics, the greater the likelihood of resulting success for everyone, whatever your desired end-game.
This may seem somewhat utopian, but elitism will get us nowhere, accessibility and inclusiveness just might.
The current field in football analytics is very good at many things, but not so good sometimes in identifying specific problems for which analysts may provide a partial or whole solution. Work on the latter will help further bridge the gap between analyst and club. Sometimes, it’s important for analysts to step out of R and Tableau and start to breakdown if and how clubs can actually move the needle on some of these predictive metrics. Otherwise, they are like doctors who are only able to offer a diagnosis, but not a cure.
Wise words and certainly advice that should be heeded if you are one of the many people in the market offering analytic solutions for football clubs. With such work being necessarily proprietary and the retention of a competitive edge encouraging secrecy from within clubs, it is not always obvious how analytically switched on the industry is. Leading data providers such as Opta and Prozone occasionally offer a window into the products they offer to clubs, in particular recent Prozone videos from Hector Ruiz and Paul Power showed great skill and clarity alongside the benefits and economies of scale afforded by full data access and a dedicated and skilful workforce. One presumes that by this point most clubs will have at least a small analytics department and probably a lot more. Whether such a department is fully integrated with coaching or the first team will likely vary on a club to club basis, but the point remains: analytics does not exist in a bubble, it is in place, there are professional companies that can offer a full package and access to the market from the outside is difficult. Plenty of people want to work in football and whilst smart in principle, co-opting a few models from other industries and creating a brand is unlikely to improve on what is already available. But, and I feel this is important, a desire to work in football is not the only reason people are interested in or learning about analytics.
Indeed, none of this has stopped a vibrant online amateur community from sprouting up in recent years. The advent of data sites such as Whoscored and Squawka has offered easy access to data at a level that far exceeds what was available prior. Now, anyone with curiosity can collate data from numerous competitions at a player and team level and play with it. It can be analysed and truths, both whole or partial, can be uncovered. These truths have a variable application. For some, with good technical skills, predictive modelling can inform betting, for others fantasy football. I choose to tell stories about what I've deduced and i've sunk many hundreds of hours into it because I find it interesting and intellectually rewarding. As with any subject, there is a learning curve that never ends, not everything I do hits the mark and there are few short cuts to knowledge, but as others who've done this before me have noted, you do it because it's fun.
The current situation in analytics has created different viewpoints. Firstly there is a great drive for predictability, repeatability and application. These are entirely logical and commendable aims, but the arms race to maximise these effects has lead to a shroud being laid over the details involved. In particular, and with one notable exception from Michael Caley, the multiple black box Expected Goals models and advanced derivatives regularly cited have obfuscated analysis due to their non-standardisation. This is not criticism of any specific model, many hours of hard work and theoretical analysis will have gone into each by people with far more advanced skills than myself and those with such access have doubtless found multiple utilities for insight gained. My concerns lie around accessibility and interpretation and this is where I feel some parts of the analytics community have missed the point.
Barriers to entry may have reduced over time, but barriers to understanding have not. There is no such thing as an "Expected Goal", it is entirely theoretical. A layman interested in football statistics may not yet understand the value of a shot or a shot on target yet he is quickly encountering hypothetical versions of the things he does understand: goals. That is a tough sell. Shot counts are real and easily understandable, they aren't "outdated" metrics, they are the building blocks of all that comes after and if the analytics community has any interest in popularising it's method of thinking and transcending a niche corner of football, the stories told by our fundamental metrics are intrinsic.
And there are many stories to be told. Variance in league seasons of 34 to 46 games is huge. Half and whole seasons can go by where the measurable statistical reality of a team is skewed vastly in either direction. Liverpool's huge overachievement of 2013-14 followed by an almost inevitable regression this season, just one obvious case. It isn't just the board that need to understand the wider implication of such matters, the fans can benefit too. Interpretations may differ but we can pull apart possible reasons in the numbers and disseminate the knowledge. Oh for a day where the average pre-game conversation involves an understanding that a team's save percentage has been unsustainably high or a striker gets cheers rather than murmurs or abuse because fans understand he's been unfortunate rather than inept.
It's probably a long way off but as each year passes, we collect more data and we can test more outcomes. Our knowledge can grow and with it our expertise and ability to inform. It is important to encourage people new to the movement and support their effort. We may strive for professionalism but we all start as amateurs. Guide rather than chastise and realise that the more people that are interested in football statistics and analytics, the greater the likelihood of resulting success for everyone, whatever your desired end-game.
This may seem somewhat utopian, but elitism will get us nowhere, accessibility and inclusiveness just might.
Wednesday, 4 March 2015
A few EPL shooting graphs
Messing about with the 'detailed' tab on Whoscored can be quite interesting and that you can separate out details into 15 minute segments of games allows us to look at rates for different parts of a game. What do teams do and when do they do it? I'll present these generally as informative with a little light analysis where I feel something is relevant but having looked at it, I've not the time to make much more of it, so take what you can.
Shots by time period
Percentage of shots in each half
Percentage of shots in first 30 minutes
Who tries to start fast?
Percentage of shots in last 30 minutes
Kitchen sink time at Loftus Road?
Anfield roar?
Fergie, sorry, Van Gaal time?
I've got a loose working theory that a blocked shot can be attributed to some degree to poor choice from the player, at least over large samples. In contrast, 'on target' shots have been shown at team level to be of high value, repeatable and predictive. Somewhat closer to a blocked shot in terms of value would be an 'off target' shot, I imagine a high degree of variance in 'value' dependent on how far off target the shot is. Anyway just thoughts, but from this, I posit that a team that finds a low percentage of its shots blocked may be taking 'smart' shots. It may be refusing a poor value, likely-blocked shot and continuing to keep possession, only shooting when sufficient space becomes available. So we have a simple measure, the difference in percentage points between a team's rate of 'on target' (smart) shots and 'blocked' (stupid) shots.
So just a quick post, bit of food for thought?
Cheers!
Thanks for reading!
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I've got an article on '"Arsenal, Score Effects and a Season Of Two Halves" up at Statsbomb, give it a whirl!
The weekly column resides over there now too.
Shots by time period
- Injury time an obvious factor
- Desperation?
- Early shots more speculative? We've all seen a player hit a 30 yard 'sighter' early on.
- Blocked results not intuitive here? I might have expected them to rise later on.
Percentage of shots in each half
- Every team takes more shots in the second half than the first half.
Percentage of shots in first 30 minutes
Who tries to start fast?
Kitchen sink time at Loftus Road?
Anfield roar?
- Villa tail off horribly as the game goes on. Something Sherwood will need to target. Fitness?
I've got a loose working theory that a blocked shot can be attributed to some degree to poor choice from the player, at least over large samples. In contrast, 'on target' shots have been shown at team level to be of high value, repeatable and predictive. Somewhat closer to a blocked shot in terms of value would be an 'off target' shot, I imagine a high degree of variance in 'value' dependent on how far off target the shot is. Anyway just thoughts, but from this, I posit that a team that finds a low percentage of its shots blocked may be taking 'smart' shots. It may be refusing a poor value, likely-blocked shot and continuing to keep possession, only shooting when sufficient space becomes available. So we have a simple measure, the difference in percentage points between a team's rate of 'on target' (smart) shots and 'blocked' (stupid) shots.
- It's is pleasing that the prescriptive football of Van Gaal, Koeman and Mourinho is represented at the top.
- It is also pleasing that the 'run around a bit' football of Redknapp is represented at the bottom.
So just a quick post, bit of food for thought?
Cheers!
Thanks for reading!
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I've got an article on '"Arsenal, Score Effects and a Season Of Two Halves" up at Statsbomb, give it a whirl!
The weekly column resides over there now too.
Friday, 20 February 2015
Thoughts on PDO
I'm going to presume if you're here that you know a bit about PDO
*cue sage nodding*
or at least what it stands for.
*silence*
It doesn't stand for anything, but we'll not get hung up on that. That's the NHL's job, for now. James Grayson popularised its use in football (indeed, his treasure trove blog houses 57 articles on the subject, if you're not up to speed spend a weekend over there!) and it is a very useful tool that helps describe teams that appear to be over or underachieving in relation to some of their underlying numbers.
For example, since losing to Man City and only recording one defeat in 15 games since, Man Utd have had a giddily high PDO rating; a clear example of a team that is overperforming against reasonable expectation. Arsenal have put up solid shot numbers, certainly better than last season, when high PDO kicked them nominally into title contention. Later it cooled a little, they dropped off and found their way back to 4th, a more accurate reflection. This year their PDO has been in the bin and they're two points behind Utd despite projecting to be much better, and are down in amongst the CL pack.
More examples? West Ham have spent the whole season with a high PDO, as have Swansea. They look to be having good years. Moreso than say Newcastle or Stoke, who are both generating a low figure. I suspect the general skill level of these four teams to be broadly similar (In fact a model i've built ranks Stoke 9th, Newcastle 10th, West Ham 11th and Swansea 14th) and the divergence from baseline numbers can at least be partially explained by PDO variance.
So what we have is a good storytelling aid which I find interesting and good fun.
"But the table doesn't lie"
*grits teeth*
No, but it doesn't reveal all it's truths either...
Despite generally liking PDO (and in amongst the stats community not everyone does) I do have issues with its current construction. Because it has been ported straight over from hockey, parts of it's derivation have been left unquestioned and I think there are a couple of subtle tweaks which may enhance general understanding. You say tomato, I say tomato. Hmm... doesn't work so well on paper.
Never mind.
As it stands PDO is:
(goals for divided by shots on target for) plus (saves divided by shots on target against)
AKA
(shooting%) plus (save%)
...then you get a grey area where some people multiply the derived figure by 1000, some by 100 or others, well, me at least, leave it as a decimal.
Immediately in the definition and the creation of the number, we have a couple of issues.
So we have elements of "this is the way it's done because this is the way it's always been done."
That's not intrinsically bad, but to me we have these figures orbiting around seemingly meaningless totals:
"PDO is 102!"
"One hundred and two whats?"
"Man Utd are at 1120!"
"I'll fit my brunch in beforehand."
Can anything be done simplify matters?
I am presuming there was a comfort found in adding your team's shooting percentage to it's save percentage; you have built a single figure for your team and you are defining what your team is doing but I feel there is more clarity in the entirely related but subtly different:
"What is my team doing and what is the opposition doing against us?"
I propose this, and I propose it with goodwill but little expectation:
(goals for divided by shots on target for) minus (goals against divided by shots on target against)
AKA:
(shooting % For) minus (shooting% Against)
This does two things:
"We are neither positive or negative! We perform exactly as you might suspect! We are a zero team!"
I'd recommend leaving it as a two digit decimal. In football, PDO variance rarely requires the precision for further digits that hockey desired. A decimal is also, and again we're basing things on simple logic, the number derived from the calculation. No further work is required.
There is plenty of work to be done to cross-over many of the metrics used in analytics and there is great complexity in a lot of the modelling that goes on. Such work is invaluable and important but often lives in a realm beyond average understanding. In order to attempt bridge the gaps between scepticism and reticence and understanding and adoption, existing metrics need to offer as much clarity as possible and hopefully i've shown that there are methods that can increase this without the need for structural change.
Thanks for reading!
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Nowadays, you will find my weekly Premier League Round-up over on STATSBOMB and assorted player and team articles as and when I get round to them. This was initially supposed to be a quick 500 word idea, but i've doubled that and being a bit speculative, I thought i'd put it back here on the rickety old blog. Plus I know (two or three) people miss reading articles on a pink background (mobile only!) so it's one for the veteran visitors.
I'd like to thank my family, the cat and Acer computers for providing support and er... a computer in exchange for money. Until next time.
*cue sage nodding*
or at least what it stands for.
*silence*
The @espnmag analytics issue (incorrectly) explains that PDO stands for Percentage Driven Output.
— Matt Cane (@Cane_Matt) February 19, 2015
It doesn't stand for anything, but we'll not get hung up on that. That's the NHL's job, for now. James Grayson popularised its use in football (indeed, his treasure trove blog houses 57 articles on the subject, if you're not up to speed spend a weekend over there!) and it is a very useful tool that helps describe teams that appear to be over or underachieving in relation to some of their underlying numbers.
For example, since losing to Man City and only recording one defeat in 15 games since, Man Utd have had a giddily high PDO rating; a clear example of a team that is overperforming against reasonable expectation. Arsenal have put up solid shot numbers, certainly better than last season, when high PDO kicked them nominally into title contention. Later it cooled a little, they dropped off and found their way back to 4th, a more accurate reflection. This year their PDO has been in the bin and they're two points behind Utd despite projecting to be much better, and are down in amongst the CL pack.
More examples? West Ham have spent the whole season with a high PDO, as have Swansea. They look to be having good years. Moreso than say Newcastle or Stoke, who are both generating a low figure. I suspect the general skill level of these four teams to be broadly similar (In fact a model i've built ranks Stoke 9th, Newcastle 10th, West Ham 11th and Swansea 14th) and the divergence from baseline numbers can at least be partially explained by PDO variance.
So what we have is a good storytelling aid which I find interesting and good fun.
"But the table doesn't lie"
*grits teeth*
No, but it doesn't reveal all it's truths either...
Despite generally liking PDO (and in amongst the stats community not everyone does) I do have issues with its current construction. Because it has been ported straight over from hockey, parts of it's derivation have been left unquestioned and I think there are a couple of subtle tweaks which may enhance general understanding. You say tomato, I say tomato. Hmm... doesn't work so well on paper.
Never mind.
As it stands PDO is:
(goals for divided by shots on target for) plus (saves divided by shots on target against)
AKA
(shooting%) plus (save%)
...then you get a grey area where some people multiply the derived figure by 1000, some by 100 or others, well, me at least, leave it as a decimal.
Immediately in the definition and the creation of the number, we have a couple of issues.
- Why are we adding entirely different aspects together? (shooting% and save%)
- Why isn't there a standardised numerical format?
So we have elements of "this is the way it's done because this is the way it's always been done."
That's not intrinsically bad, but to me we have these figures orbiting around seemingly meaningless totals:
"PDO is 102!"
"One hundred and two whats?"
"Man Utd are at 1120!"
"I'll fit my brunch in beforehand."
Can anything be done simplify matters?
I am presuming there was a comfort found in adding your team's shooting percentage to it's save percentage; you have built a single figure for your team and you are defining what your team is doing but I feel there is more clarity in the entirely related but subtly different:
"What is my team doing and what is the opposition doing against us?"
I propose this, and I propose it with goodwill but little expectation:
(goals for divided by shots on target for) minus (goals against divided by shots on target against)
AKA:
(shooting % For) minus (shooting% Against)
This does two things:
- We are no longer orbiting around an arbitrary number, we are centering around positive or negative. A high PDO will be positive and a low PDO will be negative. Understanding is relatable here, we have the universal law of goal difference: positive is good, negative is bad. It makes sense.
- We are combining the For and Against aspect of the same metric. Just as we subtract Goals Against from Goals For to create Goal Difference, we do the same to create PDO or "Shooting% difference".
"We are neither positive or negative! We perform exactly as you might suspect! We are a zero team!"
I'd recommend leaving it as a two digit decimal. In football, PDO variance rarely requires the precision for further digits that hockey desired. A decimal is also, and again we're basing things on simple logic, the number derived from the calculation. No further work is required.
There is plenty of work to be done to cross-over many of the metrics used in analytics and there is great complexity in a lot of the modelling that goes on. Such work is invaluable and important but often lives in a realm beyond average understanding. In order to attempt bridge the gaps between scepticism and reticence and understanding and adoption, existing metrics need to offer as much clarity as possible and hopefully i've shown that there are methods that can increase this without the need for structural change.
Thanks for reading!
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Nowadays, you will find my weekly Premier League Round-up over on STATSBOMB and assorted player and team articles as and when I get round to them. This was initially supposed to be a quick 500 word idea, but i've doubled that and being a bit speculative, I thought i'd put it back here on the rickety old blog. Plus I know (two or three) people miss reading articles on a pink background (mobile only!) so it's one for the veteran visitors.
I'd like to thank my family, the cat and Acer computers for providing support and er... a computer in exchange for money. Until next time.
Sunday, 11 January 2015
***Transfer news***
****IMPORTANT ANNOUNCEMENT****
'The Big Ripple' would like to announce the transfer of the weekly round-up column to the larger Statsbomb franchise. We felt unable to turn down the offer made by franchise owner Ted Knutson and as such 'The Big Ripple' would like to extend thanks for your support since it's inception a little over 10 months ago and promises to return with further content as and when it thinks of things.
The column will remain as prior with the same blend of stats, mild humour and Tottenham sections (but not when they've just lost to Crystal Palace and Alan Bloody Pardew) and will hopefully be available from early on a Monday morning.
It is hoped that this transfer will be more akin to Alexis Sanchez than Fernando Torres.
So: Monday morning, here:
http://statsbomb.com/
Thanks again!
'The Big Ripple' would like to announce the transfer of the weekly round-up column to the larger Statsbomb franchise. We felt unable to turn down the offer made by franchise owner Ted Knutson and as such 'The Big Ripple' would like to extend thanks for your support since it's inception a little over 10 months ago and promises to return with further content as and when it thinks of things.
The column will remain as prior with the same blend of stats, mild humour and Tottenham sections (but not when they've just lost to Crystal Palace and Alan Bloody Pardew) and will hopefully be available from early on a Monday morning.
It is hoped that this transfer will be more akin to Alexis Sanchez than Fernando Torres.
So: Monday morning, here:
http://statsbomb.com/
Thanks again!
Friday, 2 January 2015
19 Games
Halfway through the season seems a good time to compare this season & the teams competing within it to others. Maliciously, the Premier League has already played the 20th round of fixtures, and played it so quickly that i'm behind, but still, it's worth a look at some historical trends & markers. I've got the last 6 first half seasons I can compare & rank & this article is designed to look at some of the characteristics 2014-15 has & compare with the 5 seasons that preceded it. Data for previous years is under-available! This gives us a sample of 120 & all rankings will be 'nth in a sample of 120'.
Chelsea v Man City
For the first time since 2011-12 we look to have a potentially enthralling 1v1 dual for the title. Last season had Arsenal top at this point & Livepool's charge was late & long whereas 2012-13 was Man Utd's stroll. 2011-12 found Man Utd & Man City locked together at the top after 19 games with identical records, a scenario that would repeat right down to the last minute of stoppage time in the very last game & Aguero's late title winner. The two sides ended up 19 points clear that year (both on 89 v 70 next best) & this year is shaping up similarly but with Chelsea replacing Utd in the mix. Indeed, Chelsea's 46 point total after 19 games is only matched by Ferguson's legendary swansong & City's 43 points is only superceded by the aforementioned & the 2011-12 pair. These are clearly two elite level teams & are superior to the rest of the league by a clear margin. What fascinates me is how closely they resemble each other in the numbers & despite the media & casual observers happily coronating Chelsea since roughly late August, it leads me to believe that they are likely to push each other throughout.
*Of course since I wrote this, Chelsea & Man City have managed to accrue identical records, which more than reasserts my point!
Shots For
There are no historically strong pure shots teams in the league this year, the best teams rank as follows:
In fact, there's has been a trend towards less shots over time with quite a big drop off this year. There's a possibility methods of collecting could have changed but without knowing that we have a clear trend:
Shots Against
For there to be balance in the universe we need an equal opposite & conveniently we find similar but opposite trends in shots against. There are no historically terrible shots against teams:
Quite naturally, these figures map themselves onto shots on target:
Shots on Target For
Best:
Best:
Shot Ratios
(TSR & SoTR)
At the extremes, only Chelsea's shot on target ratio stands out as significantly high. Arsenal, Man City and Southampton round out the best 4 clubs here & each has decent if not outstanding figures. Similarly, the batch of worst teams are much of a muchness here, without being historically awful.
Save%
Everton's save percentage is the worst on record. Roberto Martinez is also responsible for 4th, 7th, 18th & 30th positions whilst at Wigan. Under par & worrying for Everton's current predicament. Intriguingly, given the 'Pardew situation' Newcastle & Crystal Palace round out this season's top 3, in 6th & 9th overall. Bad figures that may well improve but partially underline the problems Pardew both faces & has created himself. In 2005-6 he guided West Ham for half a season to terrible totals then took over at Charlton & couldn't keep them up...
Man Utd, Aston Villa, Swansea & West Ham are running the highest save percentages, none of which is historically high but it will have helped some of their current success. It's perfectly possible that these percentage could remain high throughout the season, but the list of teams that have recorded very high save percentages is littered with teams that generated a good year off the back of this & failed to follow it up once a degree of readjustment hit the following season.
One such example is... er.. Everton 2013-14 (75%).
Conversion % For
Aston Villa & Burnley are running at about 6% conversion at the half way point (quickly redeemed by Burnley in week 20!) and rank 119th/120 and 116th/120 respectively. This is very bad. Even worse when factored against the relegation rate for seasonal 6% shooters: 3/3. Limping to 7% or better would be a big help.
A clutch of teams are all running decent percentages:
League average is 10%. Some of these teams are the true elite, some of them are experiencing good seasons driven to a degree by fortune & the other team is Everton.
Conversion dominance
There are 7 teams in that chart above & 6 of them are backing up their excellent but possibly short lived high conversion rates with a similarly excellent low conversion % against ranging from 7-9%. Some of these are the true elite, some of them are teams experiencing good seasons driven to a degree by fortune & the seventh team is Everton.
Everton are the only one of these 7 to not have a conversion dominance & are conceding at a league high rate of 13%. Put simply, at various times, the goals have flown in at both ends in Everton games.
There are no historical outliers on either the good or bad sides here but WBA, QPR & Burnley are all running high deficits here & Newcastle & Liverpool aren't too far behind them. The story of conversion is a powerful one when understanding the relative successes of teams during a season. It can vary wildly & quickly but mid-term trends can be extremely informative when stood against a wider context.
Other bits
As an indicator of how vulnerable some statistics can be to one game, week 20 had a few notable entries, none more influential that the Tottenham v Chelsea game which hacked a good few chunks from Chelsea's excellent defensive numbers, in particular (average shots on target rose from 2.5 to 2.8) whilst giving a much needed boost to Tottenham's generally average figures.
Elsewhere, Villa's 0-0 has seen their conversion rate drop back down to c.5%. With a pitiful 11 goals somehow powering a half decent points total, they face an arduous season. In contrast, by scoring 3 at Newcastle, Burnley broached the magical 7% mark for the first time since the first game. If they can stay above it, they've got a chance. Meanwhile, Palace look like they need a Pulis but are gonna get a Pardew & WBA have hired the right guy; never pretty but highly effective, his teams have always managed to build from a defensive base & outperformed woeful attacking figures. West Brom's opponents are unlikely to be scoring at 12% for long. Palace's conversion went from 6%F/11%A to 8%F/9%A under him last year & his Stoke teams never once conceded at above league average rates or ran a conversion deficit of any significance.
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Thanks for reading!
FA Cup this week & the normal blog will reappear as per usual after the next round of league matches.
Thanks for reading & if you liked it feel free to share!
Meanwhile: if you missed them:
'Unlucky Neil Warnock'
'Yuletide Round Up'
& the article that killed of Pardew (maybe)
Chelsea v Man City
For the first time since 2011-12 we look to have a potentially enthralling 1v1 dual for the title. Last season had Arsenal top at this point & Livepool's charge was late & long whereas 2012-13 was Man Utd's stroll. 2011-12 found Man Utd & Man City locked together at the top after 19 games with identical records, a scenario that would repeat right down to the last minute of stoppage time in the very last game & Aguero's late title winner. The two sides ended up 19 points clear that year (both on 89 v 70 next best) & this year is shaping up similarly but with Chelsea replacing Utd in the mix. Indeed, Chelsea's 46 point total after 19 games is only matched by Ferguson's legendary swansong & City's 43 points is only superceded by the aforementioned & the 2011-12 pair. These are clearly two elite level teams & are superior to the rest of the league by a clear margin. What fascinates me is how closely they resemble each other in the numbers & despite the media & casual observers happily coronating Chelsea since roughly late August, it leads me to believe that they are likely to push each other throughout.
*Of course since I wrote this, Chelsea & Man City have managed to accrue identical records, which more than reasserts my point!
Shots For
There are no historically strong pure shots teams in the league this year, the best teams rank as follows:
- Arsenal: 23rd/120
- Man City: 24th
- Chelsea: 26th
- Aston Villa: 120th/120
- Hull: 119th
- Palace: 111th
In fact, there's has been a trend towards less shots over time with quite a big drop off this year. There's a possibility methods of collecting could have changed but without knowing that we have a clear trend:
Shots Against
- Burnley: 93rd/120
- Leicester: 85th
- QPR: 84th
- Southampton: 1st/120
- Arsenal: 4th
- Chelsea: 5th
Quite naturally, these figures map themselves onto shots on target:
Shots on Target For
Best:
- Chelsea: 15th/120
- Arsenal: 21st
- Man City: 24th
- Hull: 117th/120
- Aston Villa: 116th
- Burnley: 115th
Best:
- Chelsea: 1st/120 (immediately ruined by the Tottenham game!)
- Southampton: 3rd
- Man City: 5th
- QPR: 106th/120
- Burnley: 92nd
- Sunderland 81st
Shot Ratios
(TSR & SoTR)
At the extremes, only Chelsea's shot on target ratio stands out as significantly high. Arsenal, Man City and Southampton round out the best 4 clubs here & each has decent if not outstanding figures. Similarly, the batch of worst teams are much of a muchness here, without being historically awful.
Save%
Everton's save percentage is the worst on record. Roberto Martinez is also responsible for 4th, 7th, 18th & 30th positions whilst at Wigan. Under par & worrying for Everton's current predicament. Intriguingly, given the 'Pardew situation' Newcastle & Crystal Palace round out this season's top 3, in 6th & 9th overall. Bad figures that may well improve but partially underline the problems Pardew both faces & has created himself. In 2005-6 he guided West Ham for half a season to terrible totals then took over at Charlton & couldn't keep them up...
Man Utd, Aston Villa, Swansea & West Ham are running the highest save percentages, none of which is historically high but it will have helped some of their current success. It's perfectly possible that these percentage could remain high throughout the season, but the list of teams that have recorded very high save percentages is littered with teams that generated a good year off the back of this & failed to follow it up once a degree of readjustment hit the following season.
One such example is... er.. Everton 2013-14 (75%).
Conversion % For
Aston Villa & Burnley are running at about 6% conversion at the half way point (quickly redeemed by Burnley in week 20!) and rank 119th/120 and 116th/120 respectively. This is very bad. Even worse when factored against the relegation rate for seasonal 6% shooters: 3/3. Limping to 7% or better would be a big help.
A clutch of teams are all running decent percentages:
Conversion dominance
There are 7 teams in that chart above & 6 of them are backing up their excellent but possibly short lived high conversion rates with a similarly excellent low conversion % against ranging from 7-9%. Some of these are the true elite, some of them are teams experiencing good seasons driven to a degree by fortune & the seventh team is Everton.
Everton are the only one of these 7 to not have a conversion dominance & are conceding at a league high rate of 13%. Put simply, at various times, the goals have flown in at both ends in Everton games.
There are no historical outliers on either the good or bad sides here but WBA, QPR & Burnley are all running high deficits here & Newcastle & Liverpool aren't too far behind them. The story of conversion is a powerful one when understanding the relative successes of teams during a season. It can vary wildly & quickly but mid-term trends can be extremely informative when stood against a wider context.
Other bits
- WINS: 11 wins all but guarantees top 4, only Chelsea & Man City qualify
- GOALS FOR: 40+ goals? ^ditto
- GOAL DIFFERENCE: +14 has been enough for top 4 since 2009, Southampton AND Man Utd join City & Chelsea in passing this test.
- POINTS: Everton 2013-14 are the only team to have more points than Man. Utd (37 to 36) & not qualify for the top 4.
As an indicator of how vulnerable some statistics can be to one game, week 20 had a few notable entries, none more influential that the Tottenham v Chelsea game which hacked a good few chunks from Chelsea's excellent defensive numbers, in particular (average shots on target rose from 2.5 to 2.8) whilst giving a much needed boost to Tottenham's generally average figures.
Elsewhere, Villa's 0-0 has seen their conversion rate drop back down to c.5%. With a pitiful 11 goals somehow powering a half decent points total, they face an arduous season. In contrast, by scoring 3 at Newcastle, Burnley broached the magical 7% mark for the first time since the first game. If they can stay above it, they've got a chance. Meanwhile, Palace look like they need a Pulis but are gonna get a Pardew & WBA have hired the right guy; never pretty but highly effective, his teams have always managed to build from a defensive base & outperformed woeful attacking figures. West Brom's opponents are unlikely to be scoring at 12% for long. Palace's conversion went from 6%F/11%A to 8%F/9%A under him last year & his Stoke teams never once conceded at above league average rates or ran a conversion deficit of any significance.
---------------------------------------------------------------
Thanks for reading!
FA Cup this week & the normal blog will reappear as per usual after the next round of league matches.
Thanks for reading & if you liked it feel free to share!
Meanwhile: if you missed them:
'Unlucky Neil Warnock'
'Yuletide Round Up'
& the article that killed of Pardew (maybe)
Monday, 29 December 2014
The Big Ripple Yuletide Premier League Round Up
Arsenal/Liverpool
Three teams have won both their Christmas fixtures so far: Stoke, Liverpool and Arsenal, so why would I use now as an opportunity to cast aspersions over their prowess? Mainly becuase there is a newly franked problem at Arsenal & it needs highlighting. All year long, Arsenal have been posting excellent underlying shot totals. Their results have lagged behind but it has clearly looked like Arsenal are a strong team who will eventually reap the benefit of posting these strong numbers.
Until recently that is:
The lovely huge initial gaps between the blue & yellow line & the red & green line are 'massive shot domination' AKA 'where analytics types like Arsenal'. The recent convergence of lines is the opposite. 'But they've had a hard schedule!' shouts someone at the back. 'No they haven't, it's been kind of middling' is the correct reply. They've won 5/7 but have played at WBA, Stoke, Liverpool & West Ham & had home fixtures against QPR, Newcastle & Southampton & have posted 4 narrow wins.
Are the injuries finally catching up? A busy schedule for a stretched squad may well have impacted here. Flamini is functional but not the answer in central midfield, even Rosicky & Coquelin got starts which is a real sign of bare bones & the defensive absences have been relentless. Finally, a recognised back 4 started against West Ham but for now, it seems the early season ability to stop shots has gone. And whilst shots aren't everything, it's fair to say there are concerns.
Trips to Southampton & Man City aren't too far away either, so it's not getting easy any time soon.
Liverpool appear to be on the opposite trajectory, having spend a good 6-8 weeks living in the doldrums, the Christmas form & just before has shown great promise. Rodgers, by now many chapters into his 'Championship Manager '01/02 Formations' book, has settled on this 3-4-3 which has alternatively given no role to either strikers or wing backs, of which they have plenty that now sit on the bench, with or without Steven Gerrard. Has he lucked in? Possibly, but certainly as I showed HERE a few weeks back, Rodgers has a very good record of getting his teams to improve as seasons progress & the performance against Swansea, whilst showing characteristic vulnerability at the back was blessed with bravura & attacking charm too. Here's their same shot chart:
Mario fuelled some early shot dominance & the bad period was very bad, but lo! Do we see the green shoots of recovery? 77 shots & 33 on target in the last 4 games against 45 & 13, including a non-event against Burnley but matches against Arsenal & Man Utd is exactly what Rodgers wants his team to look like. And some of the results are following as indeed they really should in the near future as Leicester, Sunderland & Villa lie ahead.
Everton
Fulfilling my promise to write about teams i've neglected this season, we find an apt time to talk about Everton. Rooting around last night, I spotted that Roberto Martinez teams have a habit of posting extremely low PDO scores:
So, we're in a situation where Martinez needs more & might not be able to find it. His expensive striker appears to have wilted, he has excellent full backs & otherwise very young or very old players. A weird mish-mash that is currently finding it hard to create any solidity. Weirdly, the save percentage is so low that only Chelsea have saved fewer shots & they have now exceeded Arsenal & Liverpool by having the league worst conversion against from all shots. It all looks a lot like Wigan & whilst that wasn't what Martinez was brought in to reproduce, it might be what Everton have ended up getting.
Obligatory Tottenham bit
Fan voted man of the match for the last 2 games has been Hugo Lloris, and whilst it's great to celebrate the man between the sticks now & then, it's not often the benchmark of great team performances. And that's certainly the case but, points are still racking up at a reasonable rate & the scrum of teams below the top 2 still includes Tottenham. The impending misery of a visit from Chelsea awaits but beyond that there isn't a scary fixture until February. The hope endures! Although it must be mentioned that every single underlying figure still paints this team as meh average. Let us hope a bit of steel can be found & used to keep up with the others.
I remarked before that after a slowish 5-2-5 start, Villas Boas only tasted defeat 3 more times that first season & after posting an identical 5-2-5 start, Pochettino has gone 4-2-1, with the only defeat at Chelsea. Maybe, just as it took Villas Boas time to get his ideas fully entrenched, it has taken Pochettino a similar amount of time? Whilst they've ridden their luck at times (So did AVB), the team is certainly more settled now & Adebayor, Kaboul & Capoue have been largely unsighted since the rumours of bust ups. Kane & Eriksen have become the focal point of the attack with others rotating around them & this week the media seems to have noticed that Fazio & Vertonghen are doing a decent job behind a sometimes porous central midfield. As ever the transfer window will provide intrigue in the coming weeks.
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Thanks for reading!
Feel free to share if you like!
Other things to read:
1. Poor old Neil Warnock
In which I decide Neil Warnock was unlucky
2. 'Under Pardew'
In which I hammer a nail into Alan Pardew's Newcastle coffin, I mean, Ashley must've read this, right? ;)
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