Scatter graphics: Premier League, 11 Dec 2018
With a few managers losing their jobs today and the combination of an FA Cup round and some international fixtures thinning out the domestic fixture list, it felt 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).
Man City are unsurprisingly the most dominant side in the top flight overall, with Liverpool and Chelsea their nearest challengers on this score. Meanwhile Burnley and Brighton have been on the back foot the most, while it’s a surprise to see Bournemouth also in the same quadrant despite their strong start. Equally I wasn’t expecting to see Southampton having taken more shots than Liverpool given that they’re in the relegation zone.
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:
Well that (at least partly) solves the mystery of Southampton and Bournemouth from above: the Saints’ finishing has been terrible so far, with around twice as many shots taken per goal scored than the average team, while the Cherries have been among the more clinical sides in the division. Arsenal have been the sharpest shooters of all however, netting once for every six chances they’ve created.
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:
Liverpool‘s defence are pretty special this season, having absorbed well over twice as many shots as the average club for each goal they’ve conceded. I don’t expect a number as high as 22 to be sustainable over a season, but given how few shots they allow I’d expect their defensive record to remain strong regardless. Brighton and Fulham have conceded a similarly high number of shots but with very different outcomes so far.
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 the same “top three” pattern remains from the first graphic, with Man City leading the way while Liverpool and Chelsea are the standout challengers. Burnley, Fulham and Brighton stand out as the most worrying teams – particularly in defence where they’ve allowed opponents far better opportunities than anyone else.