Scatter graphics: Championship, 19 Mar 2019
I realised over the weekend that it’s been a fair while since I updated 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).
In raw shot terms, Leeds have been the division’s most dominant side, with Brentford still close to them overall despite sitting in the bottom half. Hull meanwhile sit in the top half of the table (just) but are being out-shot to the same extent as several of the clubs battling relegation. Of the teams in the most danger, both Millwall and Rotherham look healthier here than their league position suggests, with both close to a team challenging at the top of the table.
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:
The size of the gulf between Bolton, Ipswich and the rest of the division is pretty depressing for fans of those two clubs: they create far fewer chances than anyone else and haven’t exactly been clinical when presented with opportunities. Rotherham and Middlesbrough have had similar frustrations in front of goal despite at least firing in a decent number of shots, while the low number of chances created by Hull has been offset by some sharp finishing.
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 remain a case study in resilience, having soaked up an impressive number of shots for each goal conceded. Sheffield United and Bristol City also deserve a mention for being tough to breach, while QPR, Millwall and Brentford have conceded frustratingly often given how few opportunities they usually allow their opponents.
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 – at least as well as I can measure it – then Sheffield United and Leeds are almost inseparable. Norwich, West Brom and Aston Villa have looked excellent going forward but relatively average at the back. Things don’t look any healthier for Ipswich or Bolton here, and Reading – who rank worse than either defensively – are also in a spot of trouble if something doesn’t change.