Scatter graphics: League 1, 3 Oct 2021
It feels like enough of the season has passed to justify a first 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).
Rotherham are the division’s most dominant team at the moment, followed by MK Dons, so it’s no surprise to see both in the promotion picture at the moment. Doncaster are really struggling to get shots away, while games involving underperforming Ipswich have been low on goalmouth action.
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:
Ipswich and Morecambe may not be creating many chances but thanks to some clinical finishing they still have a positive goal difference. The opposite is true for Shrewsbury and Burton, who get plenty of shots away but are around three times as wasteful at converting them into goals.
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:
Leaders Wigan have been a case study in defensive discipline, allowing few shots and making it incredibly difficult for opponents to score with the ones they do manage to fire off. Ipswich and Wimbledon have faced even fewer shots per match but have struggled to keep the ball out of their net.
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:
Adjusting for shot quality, Rotherham are way ahead of the rest and they should rise into the automatic promotion places if they can keep this level of performance up. Crewe and Doncaster are both currently in the relegation zone and it’s easy to see why here: they’ve both been off the pace so far, with the Crewe defence and Doncaster attack in particular in need of improvement.