Scatter graphics: Premier League, 18 Mar 2021
It’s been about six weeks since the last batch, so it feels like a good time to refresh 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).
Three of the traditional ‘big six’ – Man City, Liverpool and Chelsea – are vying to be the most dominant in shot terms. It’s surprise to see Brighton comfortably entrenched in the bottom right quadrant given their lowly league position. Leeds and Aston Villa have looked impressive in attack but less so in defence.
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:
Sheffield United and Fulham have both struggled to convert their chances this season, needing around six more attempts to find the net than the average side. Leicester, Everton and Tottenham meanwhile have been able to rely on 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:
Aston Villa have soaked up the most shots for each goal they’ve conceded this season, giving them one of the best defensive records despite only six clubs allowing opponents more attempts per game. Southampton meanwhile have been less than half as resilient despite only five teams facing fewer shots per match.
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, Man City lead the way at both ends of the pitch. Chelsea are almost on a par with them defensively but their attack is out on its own. on a par with Liverpool in Manchester City‘s wake. Brighton are the surprising name amongst the chasing pack here, with their results falling short of their performances overall this season. Sam Allardyce has his work cut out at West Brom given how far they are off the pace at both ends of the pitch.