Scatter graphics: League 2, 21 Mar 2016
Ahead of the Easter weekend I thought it was a good time to update the scatter graphics for League 2, which compare the attacking and defensive performance of each club. These are explained here if you haven’t seen them before.
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 Notts County have created plenty of chances this season – the fourth highest total – they’ve left themselves far too open: nobody has allowed more shots at their goal in return.
If all shots were created equal then it looks as though Yeovil should be sitting in the bottom two alongside York, rather than Dag & Red. These two have created fewer than eight shots per match and have allowed more than anyone except the aforementioned Magpies.
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:
Despite taking a similar number of shots to the Cobblers, Dag & Red have been the division’s most wasteful finishers, firing in just shy of twice as many efforts for each goal scored.
Two of the division’s most industrious attackers – Plymouth and Notts County – have been concerningly below-average at converting their chances.
While Yeovil and York have struggled to create chances, they’ve at least been relatively average at turning them 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:
Plymouth continue to soak up an impressive number of shots for each goal conceded – just under four more than the average club – although four other clubs have seen similar overall successes at the back.
The top left cluster of Northampton, Bristol Rovers, Wycombe and Oxford have all looked very solid, and if you follow the line that bisects them (and denotes a constant concession rate) down and left you find Portsmouth.
While Yeovil have allowed plenty of shots at their goal, they have at least soaked many of these up, unlike the cluster of clubs beneath them in the bottom right who have struggled to neutralise opponents this season.
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:
The six sides clustered in the bottom right look to be the division’s best all-round performers, so all are worthy of the part they are playing in the promotion race.
While Mansfield were close to Leyton Orient when we were only interested in counting shots, there’s a big difference here. This suggests that the average quality of the Stags’ chances are lower than Orient’s, while the ones they allow their opponents are higher.
York are sitting the highest here: their defence has been the division’s most vulnerable and their attack the weakest, although not by much. Both Dag & Red and Yeovil have had similar troubles up front.
Notts County and Carlisle look to have seen strong attacking showings undermined by leaving themselves open at the back – the Magpies more so – while Wycombe and Cambridge in the bottom left have both seen strong defensive performances come at the cost of their productivity up front.