Scatter graphics: Premier League, 26 Nov 2017
Here’s the first full set of Premier League scatter graphics this season, 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).
Interestingly the teams are strung out in a line to a far more uniform extent than in the lower divisions. Huddersfield and Burnley are the most notable exceptions, with the Terriers allowing little in defence but at the expense of creating less themselves while the Clarets seem happy to allow a disproportionately high number of attempts at their goal.
Man City are unsurprisingly the most dominant team overall, although Liverpool and Tottenham have taken more shots so far. Interestingly Man Utd are some way off the pace set by the aforementioned three plus Arsenal, while Chelsea look even more average in raw shot terms.
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 City again look pretty comfortable here – they’re converted chances more efficiently than anyone else so far, with neighbours Man Utd the next most clinical. The three clubs creating a similar volume of efforts to the leaders have been far less ruthless.
Crystal Palace‘s wastefulness is the reason I haven’t published a set of these before now: their shots-to-goals ratio was downright silly until their recent return to scoring form. I expect them to drop further towards the middle as the season goes on, as 20 shots per goal still feels unsustainably bad.
Both Newcastle and Southampton have created a respectable number of chances but struggled to make them count, while Brighton and Leicester look to be focusing on quality over quantity.
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:
Two defences stand out at the top of the chart for their heroics so far: both Man Utd and Burnley have absorbed over 20 efforts for each goal conceded. The Clarets’ achievements are all the more remarkable given how many shots they’ve had to deal with and given that they pulled the same stunt last season this seems like a deliberate strategy.
Bournemouth, Brighton and Swansea are also soaking up a lot of efforts, albeit to a lesser extent, while Liverpool are in the opposite camp. The Reds may not allow that many shots at their goal but the ones that do get through are converted more readily than those faced by any other top flight team 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 correct for shot quality, Man City are in a league of their own at both ends of the pitch, with four of the other ‘big six’ clustered in their wake. Chelsea are the odd one out, looking relatively average by comparison, which is not the situation you’d normally find the defending champions in.
Burnley‘s start to the season looks positively gravity-defying given that they’re allowing far better chances than they’re creating, while Everton (who have faced chances of higher quality than anyone else) and Swansea (who have created the least) have plenty to worry about.
Newcastle look to have adapted more capably than the other two promoted sides so far, while Crystal Palace don’t look anywhere near as bad as their league position suggests.
Note: For both Chelsea and Burnley I’m wondering if the fact my model uses less granular data is a factor e.g. I know from working with other datasets that Sean Dyche excels at getting defenders between the ball and the goal, which might influence the Clarets’ numbers in ways I can’t track.