Scatter graphics: League 1, 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).

Sunderland have looked the most dominant in shot terms, so it’s not been a surprise to see them make inroads in the promotion race lately. Wigan look to be in danger, having created the fewest chances per match and allowing a lot 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:

Current leaders Hull have been the most ruthless side in front of goal so far this season. Meanwhile Bristol Rovers have struggled to convert their chances this season despite creating an above-average amount, with fellow strugglers Northampton and Wimbledon also among the division’s more wasteful finishers.

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:

Sunderland and Hull have looked the most solid defensively, allowing few attempts at their goal and proving difficult to break down. Fleetwood have offered even more stubborn resistance, while MK Dons and Swindon have been breached with frustrating regularity despite not giving their opponents that many chances.

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 chance quality there aren’t any standout dominant teams, which hopefully means we’re in for a dramatic promotion race. Three of the current bottom five – Wigan, Swindon and Northampton – look to be in the most trouble based on their performances so far, having struggled at both ends of the pitch.