Scatter graphics: Championship, 18 Mar 2021

It’s been about six weeks since the last batch, so it feels 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.

Shot dominance

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).

Runaway leaders Norwich have been by far the most industrious attackers so far, while closest rivals Watford have looked a lot less dominant in shot terms. Mid-table Blackburn are also creating a lot of chances, although this has come at the cost of defensive solidity. Bristol City have spent a worrying amount of time on the back foot this season.

Attacking effectiveness

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:

Wycombe have struggled to convert their chances this season with no attack being more wasteful, although the two East Midlands clubs have also had issues up front. Bristol City may have created little but only Brentford have been more clinical in front of goal.

Defensive effectiveness

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 top three of Norwich, Watford and Swansea have all excelled at keeping the ball out of their net this season, relying on resilience rather than restricting the number of shots they’ve faced. Barnsley meanwhile have made it difficult for their opponents to shoot but struggled to contain the chances they do face.

Expected goals

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, Norwich‘s attack remains way out in front, although their defence looks a lot more average. Bristol City are an enigma as they sit comfortably in 13th despite posting worrying numbers at both ends of the pitch, so perhaps they’re doing something that the data isn’t picking up.