Scatter graphics: League 2, 29 Oct 2017

Here’s another update to 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.

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).

Coventry are the most dominant side overall – and by quite a distance – taking just under 14 shots per match and allowing just over half as many in return. A cluster of teams can match their attacking output but none of these can touch them defensively.

Forest Green‘s recent improvements mean that there’s no one team that stands out as the least dominant, although Morecambe are once again allowing opponents plenty of opportunities.

Both Stevenage and Exeter could see their promotion ambitions thwarted by overly-permissive defences, but at least their matches are providing plenty of entertainment. There’s far less to get excited about at Port Vale, who allow relatively few chances but don’t create much themselves.

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:

I was wondering how Notts County were sustaining a promotion challenge off the back of such a modest number of chances and here’s at least part of the answer: only Yeovil and free-scoring Luton have converted shots into goals more efficiently so far.

While Coventry dispatched the Hatters in clinical fashion this weekend, overall they’ve struggled to make their chances count: only Crawley and Morecambe have been more wasteful.

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:

Coventry‘s defence has looked impressive from the beginning – they’ve allowed far fewer shots than anyone else and are the division’s most resilient at soaking up their opponents’ efforts.

While Wycombe have looked impressive up front (see last chart) and are the division’s top scorers, a defence as leaky as struggling Port Vale‘s has kept their goal difference relatively modest.

Exeter‘s stubborn defence has sustained their promotion challenge so far and they’ve absorbed plenty of shots for each goal conceded, while Cambridge are goal kryptonite so far with the ball averse to finding its way into the net at either end of the pitch.

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:

While Coventry have looked the most impressive overall, their attack has looked pretty average compared to that incredible defence, so it remains to be seen whether they can score enough goals to see their dominance pay off.

The reverse is true of Exeter and Newport, whose defences have looked vulnerable enough to cancel out a lot of the good work being done further forward.

Cheltenham look to have put last season’s struggles behind them and seem like a good outside bet for the play-offs on this evidence, while – despite a few recent wins – Forest Green still look to be in the most trouble overall.