Scatter graphics: Premier League, 14 Dec 2021
It’s been inexcusably long since I refreshed the scatter graphics, so here’s a full pre-Christmas set. These compare the attacking and defensive performances of every team in a division – each of the four graphics is explained briefly below and at length here.
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).
As is traditional, Liverpool and Manchester City are dominating the shot counts, with the Reds more industrious in attack and City the more effective in defence. Chelsea have been their closest competitors so far, with West Ham edging the chasing pack.
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:
Norwich haven’t been that great at creating chances and they’ve really struggled to convert the shots they’ve been able to get away. Wolves and Southampton have also been wasteful in front of goal while Leicester have been making good use of a fairly average number of attempts.
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:
Chelsea may not have restricted their opponents’ chances as effectively as Manchester City but they’ve proven difficult to break down. Wolves‘ defence has been compensating for their poor attack so to keep them in the top half of the table. Everton have allowed relatively few attempts at their goal but have found it difficult to keep the ball out of their net.
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:
When we adjust for shot quality it’s again Liverpool in attack and Manchester City in defence who are streets ahead of the rest, with neither being slouches at the other end either. The current bottom two of Norwich and Newcastle unfortunately look to be there on merit, with the Wolves attack and the Leicester defence each undermining some respectable work at the other end of the pitch.