Scatter graphics: Premier League, 11 Dec 2016
With 15 rounds of matches having been played in the Premier League I thought it was time to revisit the scatter graphic templates and see how the top flight is shaping up.
Each of the four graphics is explained briefly below but there’s a longer explanation here for the curious.
First of all, here is how the number of shots taken by each club compares with those they face in return. The average number of shots taken per match is on the horizontal and the average number faced is on the vertical, so bottom right (take plenty, allow few in return) is good while top left (take few, allow plenty) is bad. The stripes are like contours: the greener the stripe, the better the performance (and vice versa for red).
Liverpool are the division’s most dominant of seven clubs in the bottom right corner who look to be controlling games far more than the other 13. Despite their indifferent start, Southampton are creating a similar balance of chances to the likes of Arsenal and Chelsea.
In the top left we find three clubs who have spent most of the season on the back foot so far: Burnley, Hull and Sunderland have all faced around twice as many shots as they’ve taken.
Now let’s look at attacking alone. The horizontal axis stays the same as in the graphic above, but now the vertical shows the average number of shots needed to score each league goal. Therefore bottom right is good (taking lots of shots and needing fewer efforts to convert) and top left is bad:
While Southampton and Arsenal are creating a similar number of chances, their fortunes in front of goal could hardly be more different. The Saints are the division’s most wasteful finishers while the Gunners have been the most clinical, needing around 10 fewer attempts to score each of their goals so far.
Man Utd and Tottenham have also struggled to convert the high number of opportunities they’ve carved out so far, while the likes of Leicester and West Brom have made the most of a more modest amount of efforts.
Next let’s look at the defensive situation – basically take the above chart and replace the word “taken” for “faced” on both axes. Now top left is good – facing fewer shots and able to soak up more per goal conceded – and bottom right is bad:
Tottenham and Chelsea look to be in the best defensive shape so far, with Middlesbrough and Burnley also soaking up plenty of punishment for each goal conceded.
While Liverpool and Man City have allowed the fewest chances, those which have gotten through have found the net worryingly frequently.
Finally here’s an attempt at correcting the first graphic for the quality of chances created and allowed, using the same “expected goals” values that power my shot timelines (explained here). The reason for doing this is that the results tend to correlate more strongly with performance than when we treat all shots equally. FYI there may be some differences with expected goals values published by other bloggers, who have access to far more detailed data than I do:
Again we find Man City and Liverpool in the bottom right: they’ve had by far the healthiest balance of chances, but that won’t count for much if they can’t plug the leaks in their defence.
In the opposite corner, Sunderland look slightly better than Burnley and Hull when we correct for shot quality, but not by much. Below them, Middlesbrough‘s attacking output is worryingly low, although they’re at least doing a decent job of restricting their opponents’ chances.
It’s been entertaining at Crystal Palace so far, with an above-average amount of chances flying in at both ends, so their 5-4 defeat to Swansea the other week now looks a bit less mysterious.