Scatter graphics: Premier League, 18 Mar 2018
I thought it was worth one more update of the scatter graphics before the end of the season. 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).
Man Utd continue to look off the pace compared to the other members of the ‘big six’, with Arsenal and Chelsea also looking less dominant overall than the remaining three.
Crystal Palace are also continuing to look better than their league position – normally I’d expect a team with those sorts of numbers to be sitting in the top half rather than struggling to avoid the drop. Huddersfield meanwhile look to be this season’s “safety first” team – creating little but allowing little in return.
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:
Here’s where it starts to go a bit wrong for Crystal Palace: despite the respectable number of shots they’ve taken they’ve been the worst finishers in the division, although a lot of this is the hangover from that awful start to the season. Newcastle and Southampton have had similar woes.
Meanwhile Man Utd are one of the sharpest finishers, which is helping them to keep pace with their goalscoring feats of their more productive rivals. Everton and West Ham have been able to rely on some clinical finishing despite creating relatively few chances.
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:
Man Utd‘s defence – or perhaps just David De Gea’s heroics – are also helping to keep them competitive at the top of the table. Only Burnley are soaking up more shots for each goal conceded so far this season, which explains how they’ve been able to concede fewer goals than Liverpool despite allowing twice as many attempts at their goal.
Brighton‘s defence is doing a similar job to the Clarets’ but in a less extreme way, while Watford and Huddersfield look to be focusing on limiting their opponents’ chances (albeit without being able to keep many of them out).
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:
Man City look far more dominant than the rest when we correct for shot quality – they’re creating around three times the quality of chances than they’re allowing, which is pretty insane. Liverpool and Tottenham are doing the best job of competing with City, with the other members of the ‘big six’ looking less impressive.
Crystal Palace and Leicester both look closer in performance terms to Man Utd than Jose Mourinho’s side do to many of their rivals. It’s also interesting to see that Southampton – like Palace – haven’t looked all that bad this season despite their relegation worries. I’m not sure whether this is just down to their wasteful attack (as seen in the second chart above) or something deeper.