Scatter graphics: Championship, 20 Dec 2020
Ahead of the festive fixtures it feels like enough time has passed to have another 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 15 shots per match while nobody else is even managing 14. Newly-promoted Wycombe are struggling to adapt, particularly in defence where they’ve allowed more shots per match than anyone else. Bristol City are currently sitting in the top half of the table despite allowing roughly 5 shots more than they take per game.
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:
Derby‘s profligate attack is breaking the graphic at the moment, with more than 20 shots taken for each goal scored. Including the Rams, four of the current bottom five are the four most wasteful finishers in the division. Meanwhile Stoke have taken fewer shots than anyone except Sheffield Wednesday but are in the promotion race thanks to some ruthless 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:
Bristol City‘s defence has been keeping them competitive, with only a handful of sides soaking up more shots for each goal conceded. Despite restricting their opponents to far fewer attempts per match than the Robins, both Barnsley and Reading have conceded five more goals in total.
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, there isn’t a clearly dominant team. Brentford and Cardiff look to be the best all-rounders, although Norwich‘s supercharged attack is comfortably compensating for a slightly permissive defence. Bottom side Wycombe look to be the most off the pace defensively, while Coventry‘s performances are also a cause for concern.