Scatter graphics: Championship, 2018/19
Now that the regular season is over, here’s a final batch of 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).
Leeds were the most dominant side overall in raw shot terms, with Brentford also standing out as having created far more chances than they faced. Relegated Bolton and Ipswich created fewer than 10 chances per match while allowing comfortably more in return. Weirdly, Rotherham and West Brom are in almost exactly the same place on this chart despite one being relegated and the other still capable of reaching the Premier League.
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:
Bolton pretty much break this graph with a horribly low conversion rate of over 15 shots for each goal scored. Middlesbrough‘s own wasteful finishing surely contributed to them missing out on the play-offs and we can see here where the fortunes of Rotherham and West Brom – the latter being the division’s sharpest finishers – diverge.
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:
Middlesbrough may have struggled to convert their chances but in true Tony Pulis style they made it even more difficult for their opponents to find the net. Sheffield United‘s defensive resilience will probably come in handy in the Premier League. Poor Rotherham were the most porous side in the division, narrowly edging out QPR who also soaked up fewer than 8 shots for each goal they conceded.
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, the actual top two of Norwich and Sheffield United are much closer to Leeds, although the latter still edge it overall as the most impressive performers. In the opposite (top left) corner, Reading were worryingly close to the bottom two in average performance, although their late surge may well be drowned out by the awfulness that preceded it. Swansea and Brentford may have missed out on the play-offs but both look to have had promising seasons that they could build on next time.