Scatter graphics: Premier League, 17 Sep 2019
As it’s been a good few years since I last gave them a polish, I’ve updated my scatter graphic templates for their first outing of the new 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.
While you can read more about them in the link above, here’s a quick summary of the main changes that have been made:
- The stripes now actually mean something – before they were useful contours but now they’ve been anchored to the historical data for each division.
- Where possible I’ve used a 16:9 aspect ratio so that the graphics fit a smartphone screen, only reverting to a retro 4:3 when the plot gets too cramped.
- The style now matches my other graphics more closely.
It’s worth flagging up front that the relative difficulty of a club’s fixtures so far can have a significant impact on where they sit at this early stage of the season.
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 once again the most dominant side, but it’s interesting to see that struggling Watford have been creating and allowing chances at a similar rate to leaders Liverpool. While Norwich have started well, they’ve taken the fewest shots and only Arsenal have allowed more 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:
The mystery of Watford‘s position on the previous chart is solved here: while they’ve done a lot of shooting, they’ve also done an eye-watering amount of missing: the Hornets’ attack has been over twice as wasteful as that of the average side. Norwich meanwhile have outscored the likes of Man Utd by being the most ruthless finishers in the top flight.
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:
The trio of Man Utd, Liverpool and Leicester are striking a nice balance between allowing their opponents few chances and repelling most of the ones that do get through. Newly-promoted Aston Villa‘s defence is having to do a lot of work but so far they’ve soaked up over three times as many attempts for each goal conceded than Chelsea.
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 are comfortably out in front, with Liverpool and Man Utd their closest challengers. Despite the hopes that Brendan Rodgers would bring more exciting football to Leicester, the Foxes’ matches look to have been the dullest in the division so far. Both of the North London clubs – Arsenal and Tottenham – appear to need some defensive improvements if they’re to challenge successfully for the top four.