Scatter graphics: League 1, 20 Dec 2020
Ahead of the festive fixtures it feels like enough time has passed to have another look at 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 have looked the most dominant in shot terms, so it’s strange to see them outside the promotion picture at the moment (albeit having played fewer matches than most of the teams above them). Meanwhile Gillingham aren’t far below the Black Cats despite allowing their opponents more shots per match than anyone else.
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:
Northampton are struggling the most up front so far, having created fewer chances per match than anyone except Wigan while also being the most wasteful at converting shots into goals. A trio of clubs – Plymouth, Sunderland and Accrington – are out-shooting the rest of the division but would be sitting higher in the table if they made more of their opportunities count.
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 may allow plenty of shots but only Portsmouth have kept a higher proportion of the chances they’ve faced out of the net. MK Dons meanwhile have shipped goals at a slightly higher rate than the Gills despite only two clubs facing fewer attempts per game so far.
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 chance quality, Wigan and Northampton look to be in the most trouble: both are creating worryingly little in attack and are among the four worst-performing defences. Sunderland moving into promotion contention wouldn’t surprise me on this evidence: they’ve comfortably out-created the rest of the division while also looking tidy in defence overall.