Scatter graphics: Championship, 2017/18
Now that the regular season is over, here’s a final batch of the scatter graphics, 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).
Brentford‘s energetic attack have stood out from the crowd with the sheer volume of shots they’ve taken this season, although as the next chart (and indeed the league table) shows, this isn’t a recipe for success by itself.
Ipswich have allowed over a shot more per game than anyone else and carved out fewer opportunities than all but two other teams, so it’s understandable that the fans weren’t opposed to a change of manager.
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:
Brentford may have taken the most shots by far, but only three teams have been more wasteful in front of goal this season. Birmingham take the cake however with over twice as many chances created for each goal scored as champions Wolves (the most clinical finishers).
Barnsley and Norwich can also point to a profligate attack to explain their disappointing campaigns, with both creating a respectable number of chances but struggling to convert them.
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:
Millwall and Cardiff both excelled at keeping their opponents’ shots out of their goal this season, while the relegated duo of Sunderland and Burton operated the division’s most porous defences.
Ipswich deserve an honourable mention for soaking up a lot of shots – they allowed around three shots per game more than the likes of Hull and QPR but conceded fewer goals overall.
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 the top two of Wolves and Cardiff look to have secured their promotion on merit. They head a cluster of seven clubs in the bottom right who look to have performed at a level above the rest of the division. Interestingly this cluster doesn’t include the play-off pair of Derby and Middlesbrough, both of whom have endured chaotic seasons.
Burton‘s relegation doesn’t look all that surprising given their position here – they did well to take the relegation battle down to the final day – while Reading and Bolton will surely be looking to ring the changes over the summer to avoid a repeat of this season.