Scatter graphics: Championship, 1 Nov 2020
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).
Blackburn and Norwich are out-creating the rest of the division by an impressive margin: both have fired in over 16 shots per match while nobody else is even managing 14. Newly-promoted Wycombe and Coventry are struggling to adapt so far, while league leaders Reading – no strangers to defying the data – have taken fewer shots than anybody else in the division.
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:
Reading are living the mantra “quality over quantity” so far, having taken needed just over 4 attempts to score each of their goals on average. This is significantly lower than the rest of the division and over 5 times better than Nottingham Forest and Derby, who have created far more chances overall but are struggling to find the net.
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:
It’s also not a surprise to see Reading overachieving defensively, although the likes of Watford and Birmingham are soaking up even more shots for each goal they’ve conceded. In the Blues’ case, they’ve been the most resilient of all despite only three clubs allowing their opponents more opportunities.
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 correct for shot quality, the overall picture is fairly similar: both Coventry and Wycombe will probably need to improve – particularly in defence – if they’re to avoid an immediate return to League 1. At the opposite end, Blackburn and Norwich may be more impressive in attack than defence but overall both should be disappointed with anything less than an automatic promotion challenge. Reading are once again defying the data: their defence has been one of the division’s best, but their attack is either running extremely hot or doing something very unusual.