Scatter graphics: League 2, 18 Mar 2021

It’s been about six weeks since the last batch, so it feels like a good time to refresh 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.

Shot dominance

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 continue to set the standard as the division’s most dominant team, so it’s surprising to see them so far off the promotion pace. Meanwhile Colchester have spent a lot of time on the back foot this season, creating little but allowing plenty of shots in return.

Attacking effectiveness

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:

Southend have had a miserable season in front of goal: creating little and struggling to convert what they have been able to carve out. Carlisle have also been wasteful with their impressive attacking output, albeit to a lesser extent, while Exeter have been the most clinical finishers so far.

Defensive effectiveness

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, soaking up almost six more shots than the average team for each goal they’ve conceded. Despite allowing few chances, Carlisle‘s defence has been the division’s second leakiest, narrowly behind bottom side Grimsby.

Expected goals

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, Carlisle are no longer the most dominant team, suggesting that some of the chances they create are of relatively low quality. Cheltenham, Newport and Forest Green look more impressive overall so should remain in the automatic promotion race.