Scatter graphics: League 2, 19 Nov 2016

It’s been roughly a month since the last set was produced, so I’ve updated the scatter graphics, each of which 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).

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While Portsmouth remain the most dominant side in the division overall, taking around twice as many shots as they tend to face in the average match, they’ve been slightly outshot by Blackpool so far.

At the top of the graphic we can see that Morecambe create a relatively average number of chances but allow far more than anyone else in return: around 17 per match, which is over five more than the average and ten more than Portsmouth.

In the bottom left corner we find Crewe, whose matches have been relatively uneventful with an average of just over 19 shots in, compared to the 25 or so that are typically fired in whenever Barnet or Luton are involved.

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:

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So while Portsmouth and Blackpool lead the way when it comes to creating chances, neither have converted theirs with particular aplomb, while Doncaster have made far more efficient use of a more modest number of efforts. It’s only taken Rovers an average of between five and six attempts to find the net compared to the nine that the average fourth tier club has required.

Only two sides have carved out fewer opportunities than Hartlepool so far, but they’ve made the most of what’s come their way, while Accrington in the opposite quadrant rank fifth for quantity of shots taken but are the division’s most wasteful finishers.

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:

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Luton‘s strong start owes much to their tenacious defence, which has soaked up over 13 shots for each goal that the Hatters have conceded: over four more than the divisional average.

Interestingly the six sides to have allowed the fewest chances have all been below-average at keeping them out of their net, with Doncaster conceding almost as readily as their opponents so far (as per the previous graph). Hartlepool have also seen goals flow readily at both ends of the pitch, so it’s perhaps no surprise that both scored when they met at the weekend.

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:

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Portsmouth’s dominance is just as pronounced when we correct for shot quality: it’s genuinely surprising that they’re 10 points behind the league leaders with performances like these.

With Accrington putting in similarly solid performances to top-of-the-table Plymouth yet sitting 15th, they also look to be underachieving significantly.

At the top of the chart, we see that Morecambe are allowing around two goals’ worth of chances per game, which surely isn’t a recipe for staying in the division even with a respectable level of attacking output.

Both Crewe and Mansfield look to be operating a “safety first” strategy: effectively limiting their opponents’ chances but at the expense of a cutting edge up front.