Scatter graphics: League 1, 2020-21
Now that the season is over (barring play-offs which I exclude for consistency), I can create final versions of the scatter graphics. 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).
Sunderland were the division’s most dominant side in shot terms, so they can be disappointed with a play-off finish. Accrington created the most chances and also allowed plenty in return, making their games great entertainment for the neutral.
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:
Bristol Rovers‘ inability to convert their chances looks to have been a big factor in their relegation, while the top two of Hull and Peterborough were the division’s most clinical finishers. Charlton and Lincoln relied more on quality than quantity up front this season.
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:
Gillingham secured a top half finish despite allowing more shots at their goal than anyone else, thanks to some resolute defending. Blackpool and Hull were the most defensively solid overall, allowing their opponents few chances and generally dealing well with what they couldn’t prevent.
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, Sunderland again edge it as the best-performing side in the division, with the actual top two their nearest challengers and the rest of the top six not far behind. Ipswich compensated for a quiet attack with a solid defence.