Scatter graphics: Premier League, 2017/18
Here’s an end-of-season update to the scatter graphics, which 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).
Five of the ‘big six’ clubs stand out as more dominant than the rest – the exception being Man Utd who are closer to the chasing pack than their nearest rival despite their second place finish. It’s actually Liverpool who have dominated the most after runaway champions Man City.
I’ve mentioned before that Crystal Palace have looked better than their results this season and they’re comfortably above average in raw shot terms, so their strong recovery from a nightmare start wasn’t surprising.
Huddersfield look to be this season’s “safety first” team – creating little but allowing little in return, while Bournemouth matches look to be good value for the neutral.
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:
Man Utd may not shoot as much as their rivals but they are one of the division’s sharpest finishers, which is helping them to keep pace with the goalscoring feats of the teams around them.
West Ham, Everton and Leicester have also been able to rely on some clinical finishing despite creating relatively few chances.
Southampton‘s poor finishing has helped to drag them into a relegation battle this term – despite creating a respectable number of chances they’ve been one of the most wasteful teams in front of goal.
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 – have also helped to keep them competitive at the top of the table. Only Burnley are soaking up a similar number of shots for each goal conceded – they’ve only conceded one more goal than Liverpool despite facing around twice as many shots.
The Reds may have a leaky back line but they allow few chances, while an unreliable defence has been a problem for Watford: the Hornets have repelled fewer shots for each goal conceded than anyone else, despite permitting fewer attempts than Arsenal.
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 created around three times the quality of chances that they allowed, which is ridiculous.
Arsenal‘s attack looks a lot more convincing than their defence, so this is an area I’d expect to see them invest in over the summer.
This chart further underlines the fact that Crystal Palace had no business being in a relegation scrap, and while Swansea and Stoke both look like relegated teams, West Brom‘s performances didn’t seem all that bad.