Scatter graphics: League 2, 2018/19
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).
Lincoln won the league with a kind of quiet effectiveness, having created almost the same number of chances as bottom side Yeovil – the next two charts will show how they managed it. Promoted alongside them, Bury produced a more traditionally dominant showing while MK Dons were the Imps’ polar opposite: allowing the 3rd most attempts at their goal but giving as good as they got.
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:
Here’s one of the stories behind Lincoln‘s promotion: an absolutely ruthless attack that took around two fewer shots for each goal scored compared to the average team. Both Cambridge and Port Vale struggled to find the net this season despite taking an above-average number of shots.
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:
Lincoln were also incredibly tough to break down, although fellow promoted side MK Dons were even more stubborn at the back despite all those shots they allowed – having watched them this season, this could be explained by them encouraging opponents shoot from poor positions. Notts County may not have faced all that many shots but a leaky defence played a huge part in their relegation: they soaked up far fewer attempts than the average team for each goal conceded.
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:
Adjusting for shot quality moves Lincoln into the ‘good’ quadrant and it looks like Mansfield should fancy their chances of joining them in League 1 next season via the play-offs. Colchester appear unlucky to have missed out on a play-off spot while Northampton‘s bottom half finish is also a bit disappointing given their performances overall. It’s not clear whether Grimsby were lucky to have avoided a relegation battle this season or if they’re doing something that the relatively simple data available to me isn’t picking up.