Scatter graphics: League 1, 10 Dec 2018
With a few managers losing their jobs today and the combination of an FA Cup round and some international fixtures thinning out the domestic fixture list, it felt 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.
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).
While their promotion challenge may be faltering somewhat, Barnsley remain the most dominant side in the division, although with high-flying Sunderland and Peterborough both having taken fewer shots than they’ve faced there’s clearly more to success than just these raw numbers.
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:
The struggles of Bristol Rovers and Wimbledon this season owe no small part to their wayward finishing, with Rovers’ predicament particularly frustrating given that only Barnsley have out-shot them so far. The aforementioned Sunderland and Peterborough meanwhile can both be thanking their clinical strikers for keeping them competitive, as can shot-shy Fleetwood.
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:
Leaders Portsmouth and third-placed Sunderland can both thank stubborn defences for absorbing plenty of the shots that they have to deal with, although Peterborough‘s have been among the most hard-working. Despite allowing relatively few attempts at their goal, the likes of Burton and Oxford have struggled to keep the ball out of their net.
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 trio of Portsmouth, Barnsley and Luton stand out as the best performers. Where it gets really strange is that the three next best – Shrewsbury, Burton and Bristol Rovers – are all in the bottom half at present, so I’m wondering whether all three will rise upwards before the end of the campaign. Fleetwood really need to do something about the quality of chances they’re creating, as they’re some way off the rest of the division as it stands.