Scatter graphics: League 1, 18 Dec 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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Sheffield United are the division’s dominant side at the moment: nobody is allowing fewer chances per game (although Rochdale and Millwall come close) while only Oxford have out-shot them so far.

It’s interesting that the Blades’ fellow title challengers are far more modestly-positioned, while MK Dons remain pretty dominant in raw shot terms despite floundering in the lower half of the table. The next few charts will help to explain this.

The likes of Peterborough and Coventry are providing entertaining fare for the neutral, creating and allowing a similarly high number of chances.

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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A few clubs stand out here. Firstly Oldham, whose awful return in front of goal is very worrying: they’ve taken over twice as many shots for each goal scored than the average side. Coventry aren’t doing all that well by this measure either, but at least they’re creating a decent number of chances.

One side who definitely aren’t carving out a reassuring number of opportunities is Port Vale. With almost four fewer shots taken per match than the average, only some clinical finishing is keeping Vale afloat at the moment it seems.

The mystery of how Scunthorpe are doing so well despite not creating an obscene number of chances can be explained by their incredibly efficient finishing: with fewer than six shots taken for each goal scored they’ve been nothing short of ruthless.

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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While Scunthorpe’s sharp finishing is allowing them to keep pace with Sheffield United, a robust defence is contributing too. However fellow title-chasers Bolton are leaning even more heavily on their back line, which is soaking up a formidable amount of chances for each goal conceded: almost double the average.

Both Millwall and Rochdale’s underachievements this season can be at least partly explained by a leaky defence, as can that of MK Dons who weren’t exactly clinical in front of goal on the last chart either.

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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Sheffield United are way out in front when we correct for shot quality, with neither of their chief rivals in the automatic promotion race dominating to anywhere near the same extent.

Concerningly for the three clubs in the top right quadrant on the first chart – Bury, Coventry and Peterborough – their attacking output looks far more ordinary once adjusted for goalscoring potential while the shots they allow still look pretty dangerous.

Walsall and Port Vale could definitely do with an injection of attacking flair to stave off the threat of relegation, while Shrewsbury need to tighten up at the back more urgently.