Scatter graphics: League 2, 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).
Carlisle‘s squad overhaul looks to have paid dividends as they – along with Forest Green and Newport – form a dominant trio of clubs who are all creating far more chances than they’re allowing. Meanwhile Colchester currently sitting in the top half of the table is surprising given how many shots they’ve allowed (and how few they’ve carved out in return).
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 horrible record in front of goal continues: similarly-attired Exeter are the division’s most clinical finishers and they’ve needed almost 10 fewer attempts to score each goal on average. Carlisle may be outshooting the rest of the pack but they’ve also been fairly wasteful – for example Colchester have the same number of goals despite taking more than 7 fewer shots per match.
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:
Salford‘s defence – or at least their goalkeeper – should be commended for being the division’s most resilient by far. It’s not clear whether they can keep soaking up so many chances successfully however. Grimsby and Barrow‘s leaky defences have left them uncomfortably close to the drop zone despite facing a below-average number of shots.
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 looks like the current top four of Newport, Forest Green, Carlisle and Cheltenham all deserve to be in the automatic promotion picture. Meamwhile Southend‘s attacking performances in particular have been responsible for their woes and it’ll be interesting to see if Colchester can continue to defy the data in mid-table.