Scatter graphics: Premier League, 7 Feb 2016
Here are updated scatter graphics for the Premier League, which compare the attacking and defensive performance of each club. These are explained here if you haven’t seen them before.
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).
Their prospects of a top four finish may be looking increasingly slim but Liverpool are still dominating matches; more so than anyone except Man City and Tottenham. All three clubs, situated in the bottom right, have taken far more shots than they’ve faced this season. However the next graphic will show how the Reds’ performances differ in a fundamentally important way.
Down in the bottom left, Man Utd have been just as difficult to break down at the back but have offered far less going forward. The opposite can be said of West Ham in the top right, who may be taking an above-average number of shots but are also allowing their opponents to run riot.
The top left of the graphic shows that it’s not been an enjoyable season for fans in the North East, with both Newcastle and Sunderland spending most of their time on the back foot.
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:
Liverpool may taken plenty of shots but they have struggled to make them count, with only bottom side Aston Villa having needed more attempts on average to score each of their Premier League goals this season.
At the bottom of the graphic we see that their neighbours Everton are one of the division’s two most clinical finishers. Alongside leaders Leicester they have taken slightly more than seven shots for each goal scored: over five fewer than the Reds have needed.
While Sunderland have shot relatively infrequently, they have at least been above average at turning their efforts into goals, as have Man Utd.
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 sides in the top right stand out: Crystal Palace and West Ham have all made a habit out of allowing – and soaking up – plenty of attempts at their goal.
Tottenham deserve a mention for the best all-round defensive performance here, allowing relatively few efforts and – alongside local rivals Arsenal – being one of the toughest sides to break down.
Bournemouth have allowed opponents similarly few chances but have struggled to keep them out, with the aforementioned two North London sides able to absorb more than twice as many shots for each goal conceded as the Cherries.
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 chance quality like this we can see that Norwich join Sunderland and Newcastle in the worrying top left corner. All three clubs are in danger of relegation if things don’t improve (although it’s unlikely that all three can be relegated given the extent of Aston Villa’s predicament).
Speaking of Aston Villa, they’ve looked relatively average at the back but have offered the least going forward this season, so it looks like their poor attack has been the biggest reason for their disastrous campaign.
In the bottom right, the three best all-round performers are the three sides immediately behind leaders Leicester: Arsenal, Man City and Tottenham. All three have put in narrowly better attacking performances than the Foxes and have restricted their opponents far more effectively overall, so perhaps there’s life in the title race yet.