Scatter graphics: Championship, 3 Oct 2021
It feels like enough of the season has passed to justify a first look at 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).
West Brom and Fulham have both dominated their matches so far and look intent on securing a return to the Premier League. Leaders Bournemouth have looked strong defensively but are creating surprisingly few chances, while Reading are just two points away from the play-offs despite facing more shots than anyone else.
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:
Bournemouth‘s attack may not be shooting much but along with Reading and Blackburn they’ve been ruthless at converting the chances they’ve had. Meanwhile Birmingham and Millwall have been creating plenty but struggling to turn their efforts into goals.
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 Derby defence has been the division’s most resilient by far this season, soaking up over 20 attempts for each goal conceded. Despite allowing the same number of shots as leaders Bournemouth, Sheffield United have conceded twice as frequently.
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, West Brom and Fulham remain the standout teams but mid-table Luton aren’t that far behind – could they be a dark horse for promotion this year? Reading continue their rich tradition of defying my expected goals model, sitting in the top half of the table despite similar performance numbers to two of the current bottom three.