Saturday, 25 November 2017

12 Game Premier League Shot Analysis

Just a quick article here, hence the old blog, I've written something similar the last three years, but am short of time, so can't do it full justice with charts and what have you. Hopefully it will provide some interesting angles you maybe hadn't considered.

We're using traditional shot metrics for a few reasons:

1. I have them stored at the 12 game point back to 2009/10, so nine seasons, which is further than semi-publicly available reliable expected goals goes back
2. I like historical comparisons
3. I like the fact that you can examine multiple aspects. A lot of xG analysis stops at over/under, and while you're not limited to that, I've got a list of about 20 separate metrics related to shots here, and it'd be rude not to share.

An aside on expected goals, which is the must dreary topic around right now, with everyone from professional pub bores to anyone with a stats orientated twitter account wading in. I think if you asked people what the most important component into a shot is, they'd reply "location" and that's fine, but pare it back and the key aspect forever more is whether or not the shot took place in the first place. Expected goals: actually built from shots, don't forget that!


Man City

No surprises here, after 12 games City are crushing a ton of shot metrics. Over the 9 seasons in the sample, shot rates overall have declined, and the very good teams seem to top out around 17 or 18 shots per game, go back to 2009/10 and it was more. Indeed of the top fifteen teams for shot volume after 12 games, only Liverpool last season and this ranks from this season or last. That makes sense, we know Klopp's team are heavy shooters but also prone to launching a fair few from range.

City's strength is both in attack and defence.
Let's just list a load of what they are scoring well in:

  • Goals: they've scored 85% of the goals in their games, ranks tied for first at this stage with Chelsea 10/11
  • Goals for: 3.3/game, 2nd behind City 11/12--we'll come back to them
  • Goals against: 0.6/game, tied 4th
  • Shots on target: 7.3/ game tied 4th
  • Shots against: 5.8/game, 1.8 ahead of the next best team in the sample, crazy good
  • Shots on target against: 1.8/90, 1st in sample by 0.3/game
  • Shot ratio: 75%, 4% ahead of the next best
  • Shot on target ratio: 81%, ~4% clear
Then we have some less structural metrics related to accuracy and conversions. You'd expect these to perhaps cool or indeed be more prone to vary. Even a team as good as City is more likely to ultimately fall within long term parameters than continue to skew positively all over, though admittedly 180 team 12 game samples leaves plenty of room for new outliers.

  • Shots on target as a percentage of total shots: 43%, 1st in whole sample, highest whole season rate is ~40%
  • The difference between that rate (43%) and their opposition (30%) ranks 1st too, at 13%, full season maximum is currently 9%
  • Shot conversion: 19% ranks 1st, full season best is about 15.5%
  • Difference between their shot conversion and the opposition is 9%, best full season is 7.3%
  • Goals per shot on target, 45%, ranks 3rd and a couple of % ahead of City's 13/14 season
So: we have on our hands a great team, that is also running hot at the extremities. This should be no surprise after watching them, but also a bit of wear and tear plus simple reversion would suggest that aspects of their game should cool a little. If they don't then we have a team for the ages. But also it's worth comparing them to City 11/12 who also started 11-1-0 and scored a ton of goals. Nobody thought that team was going to be one for the ages. They ended 28-5-5 and snuck the league on the last day. This small sample of 12 games implies City are great, but it is still a small sample--for now. 


The magic of Burnley has enchanted many this season apart from specifically me and the Everton board. They are defying relatively weak structural metrics (shots, expected goals) to ride high in the league. We know they commit to defence, but it's also true that they are riding their luck somewhat. Similar happened last season, then they eventually came back to earth, but as is likely to happen this year, they already had plenty of points in the bag and were able to limp home, with few concerns.

They have improved this season, but it's important to note they specced out as a terrible team last year. This season the specific measure that cannot--indeed will not maintain--unless we have not one but TWO "teams for the ages" in our league right now, is their opposition shot conversion. It currently is running at 4.4%, so around 1 in every 25 shots the opposition takes is scoring. This is obviously thanks to the "11 men on the goal line" strategy they have deployed and bravo for solving football.

This rate ranks 2nd of 180 behind Chelsea 2010-11 (who had a great start, that proved er... unsustainable, because, guess what! their extremely positive variance came back down to earth). It also means that Burnley are allowing goals at a lower rate than Andre Villas Boas' ill fated Spurs 13-14 team were scoring them. Yep, that's right, Burnley are facing Roberto Soldado every week and it's working out just great. The key point is that the season long lowest rate is Villa 09/10 and that ended up at 6.4%, enough to power them to 6th place--so Burnley could well end up in an extremely good place off the back of this, it's just there's plenty of juice (a whole two percentage points) in there that won't sustain. Very similar happened last year to them, but not to these extremes.

Man Utd

I'm quite down on Man Utd for similar reasons. They are scoring 16% (4th/180) of their shots and allowing 5% (3rd/180). so at both ends of the pitch, they are enjoying very positive skews in their conversions, both of which are outside full season rates. Logically, you'd expect one or both of these numbers to move as the season goes on. They are a good team sure, but a 14 to 10 shots for and against team doesn't really pass muster when we're looking for genuine dominance. They're doing fine, but i'm not gonna put any bunting out just yet. I think they are still quite flawed, and potentially the Mourinho strategic straitjacket hasn't helped either.


At least part of Watford's stellar start is down to the 48% of shots on target that are becoming goals (recall full season max is 43%). That ranks 1st of 180 here. They aren't bad, and Marco Silva has improved them, but as was mentioned last time I spoke well of them, they have started fast in previous years only to tail off. This time we have a number trigger too that could well explain some of their inevitable reversion.


...are getting 1.9 shots on target per game. This is 180th/180. Terrible.
Honestly, so bad.


7.6 shots per game against ranks 2nd/180, 43% of them landing on target ranks 180th/180, 19% of them going in ranks 179th/180. That's the Klopp conundrum right there. His teams stop the shots but the ones that arrive could be scored with a no look finish.


21% of their shots are landing on target, Not good (178th/180). Full season minimum is 25% though, so should improve.


4% of their shots are going in, yes that's AVB levels. They're scoring 20% of the goals, which is a full 5% behind anyone else in the sample. It should get better!

There's probably more, but it's Saturday morning, and the 13th games of the season are about to be played (thanks West Ham v Leicester for dating this already). Hope you enjoyed this, there's an insane, injury inducing amount of football coming up between now and the new year. A lot will change and some of these metrics will be useful indicators when teams suddenly seem better or worse than before.


All data via Opta

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