Scatter graphics: League 2, 27 Dec 2019
As we’re roughly at the halfway stage of the season, it feels worth updating 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).
Crawley stand out as a team that really loves to shoot: they’ve taken over four more shots per game than the average side, which is unusual for a team in the bottom half of the table. Also unusual is for the team which has created the fewest chances by far to be in the play-off places, although Cheltenham have compensated for a quiet attack by restricting their opponents’ chances.
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:
Stevenage’s wasteful (or unlucky, depending on your point of view) finishing is stretching the graph at the moment – they’ve needed over twice the average number of opportunities to score each goal so far, which goes a long way towards explaining why they’re bottom. We can see that while Cheltenham create little, only leaders Swindon have been more efficient at converting shots into goals.
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:
A clutch of three teams – Macclesfield, Northampton and Salford – have been working their goalkeepers pretty hard: allowing plenty of shots but repelling a high proportion of them. Leyton Orient meanwhile have struggled to keep the ball out of their net despite restricting their opponents to relatively few chances.
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:
Morecambe unfortunately look quite a way off the pace at both ends of the pitch so far: creating the worst chances on average and allowing the best in return. There’s no one stand-out team: Bradford have the most dangerous-looking attack but their defence is performing at a relatively average level, while Swindon’s rearguard is more impressive than their (still above average) forwards.