…..and other thoughts on team shooting accuracy.
In my previous article I contended that West Ham appeared to operate a deliberate “Moneyball” type strategy of trying to manoeuvre the ball into close range positions before taking a shot. In fact, so successful where they at this that they were the only team in the Premier League last season to have more than 50% of all their shots from the central portion of the Penalty Area.
As per the methodology set out in this article, I divided the shots that the teams took into 4 zones:
This inside central portion is highlighted in yellow below.
Note, as with the previous piece, I have excluded headers and penalties.
You can see just how impressive West Ham were in terms of ensuring that they took their shots from central locations within the penalty area. It’s not just that they lead the table with 51%, it’s that the gap between them and the second placed team, Stoke, at 5% is much more than the gap between any other teams in the table. They really did go to town on this particular metric.
Unfortunately for West Ham, that is where the good news ends.
Although the title of this article is tongue in cheek, I was interested in finding out why West Ham didn’t finish higher up the league table given their excellent average shooting position.
Thankfully, it didn’t take me long to find this out. Their shooting accuracy, ie the percentage of shots that they hit the target with was just plain awful.
(Apologies, but this image has gone a little awry. Not sure why this has happened but click on it to see the full table.)
The table above is sorted in descending order of overall accuracy. Man United topped the accuracy table, and in my opinion, this is the single biggest contributory reason as to why they emerged as champions at the end of the season. They didn’t have great a great Total Shot Ratio (percentage of all shots that were taken), but they made sure that their shouts counted.
We have to go a long way down the table before we find West Ham. Their accuracy at 30% is poor enough in its own right, but when you pause to think of where the majority of their chances came from that figure of 30% gets worse.
Interestingly Stoke have quite a similar profile to the Hammers, both in terms of the fact that they created a large proportion of shots from what appears to be the optimum position but also in the fact that they had a really poor accuracy ratio from those shots. Perhaps, therefore it is more than just coincidence?
As in the article where I looked at player accuracy I thought that it would be interesting to see how accurate the teams were when the location of shot was taken into account. In order not to repeat the methodology in great detail here again you can see it outlined in this article.
The league average on-target percentages for each zone are as follows:
By reference to those averages and the number of shots that each team took in each zone we arrive at the total number of shots on target expected based on league average accuracy. I then compare these expected number of shots on target to the actual number that each team achieved.
Looking right down at the foot of the table we see that both West Ham and Stoke only had 89% of the expected shots on target number. Using this measure of AR where it is adjusted for shot location, their under achievement is magnified by the fact that their shot locations should have enabled them to post higher than league average accuracy numbers. They obviously failed to achieve this.
At the top of the table, Tottenham emerge as the team that had the greatest number of shots on target in excess of what their shots would have suggested, with 14% more on target. Their rating was achieved as a result of being able to have a higher than league average on target percentage of 34%, despite the fact that they had more than 54% of their shots from outside the penalty area (only QPR had a higher proportion of their shots from outside).
As an aside, if we removed the shots that Gareth Bale took from the Tottenham shots, the Accuracy Ratio drops quite significantly to 1.03.
Back to our starting point, why did West Ham not win the league?
Although they engineered favourable looking shot positions, they were simply not able to capitalise on them by forcing the opposition goalkeepers to make a save.
Assuming that achieving a high percentage of shots from central locations inside the penalty area was a deliberate ploy from Sam Allardyce, did it backfire a little?
Perhaps their insistence on getting the ball inside the penalty area before a shot was taken was actually detrimental to their goal chances as the ball was brought into more congested areas instead of taking an earlier shot against an unprepared defence with the chance of catching the goalkeeper unaware.
At this stage, that is just speculation, but perhaps it’s something that we can look at in a future piece.
Finally, the metric of shots from prime positions is probably like most KPIs, whether they are used in business or on the sporting field. They are best used to steer the operator in the correct direction, but they need to be mindful of the impact that meeting that KPI has on the rest of the business or team.