Scatter graphics: League 1, 4 Mar 2018
As we’re at the end of the calendar year and a shade over halfway through the season, here’s another update to the scatter graphics, which 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).
Wigan remain the most dominant side in the division but out-of-sorts Peterborough have created more chances this season. Newly-promoted Portsmouth aren’t far off the Latics defensively but that’s come at the expense of some attacking guile.
Fleetwood have created worryingly few chances this season, so it’s not surprising to see them spiralling into the relegation zone. Gillingham have allowed the most shots against them by far, although – for reasons which will become clear a bit further down – it’s not doing them too much harm.
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:
Bury‘s awful season isn’t much of a mystery considering how horrific their finishing has been. Despite creating a respectable number of chances, the 16 shots they’ve taken per goal scored is four more than anyone else and over double what the likes of Blackburn have needed.
Rochdale have had similar struggles up front, although not to the same degree.
Only Fleetwood have been more clinical in front of goal than Rovers this season, with surprise package Shrewsbury similarly sharp from relatively few chances.
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 have been incredible at the back: despite allowing way more shots than anyone else, only three clubs have conceded less regularly. Wigan and Shrewsbury have been similarly tough nuts to crack, while Plymouth are another side who have rebounded from a poor start thanks to their stubborn defence.
Oldham have the leakiest back line in the division, absorbing fewer than half as many shots as the Gills for each goal conceded, with Fleetwood in the same boat.
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, both Blackburn and Rotherham aren’t looking far off the standard that Wigan have set: if these are the three clubs who gain promotion to the Championship then it will be on merit.
While Plymouth look to be in a bad place overall, they’ve made a huge improvement since the turn of the year, when they and Northampton both looked utterly screwed.