Scatter graphics: League 2, 17 Sep 2019

As it’s been a good few years since I last gave them a polish, I’ve updated my scatter graphic templates for their first outing of the new season. 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.

While you can read more about them in the link above, here’s a quick summary of the main changes that have been made:

  • The stripes now actually mean something – before they were useful contours but now they’ve been anchored to the historical data for each division.
  • Where possible I’ve used a 16:9 aspect ratio so that the graphics fit a smartphone screen, only reverting to a retro 4:3 when the plot gets too cramped.
  • The style now matches my other graphics more closely.

It’s worth flagging up front that the relative difficulty of a club’s fixtures so far can have a significant impact on where they sit at this early stage of the season.

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).

Crawley have tended to be pretty quiet in attack during recent seasons, so to see them rampaging like this is a pleasant surprise. Strangely they’re level on points with Cheltenham – the division’s most shot-shy team – at the moment, but the remaining charts will probably shed some light on that. We’ll also see how league leaders Exeter can look so average here.

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’ve had to break out the extra-tall chart to accommodate Walsall‘s horrific record in front of goal without the rest of it being an unreadable mess. The Saddlers have just 3 goals from 90 shots, which is surely unsustainable and I expect their dot to drift downwards as the season progresses. We can see that Cheltenham have been the division’s most ruthless finishers, which has compensated for the low number of shots they’ve taken, while poor finishing is also costing the likes of Stevenage and Colchester despite them shooting at a respectable rate.

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:

Three defences stand out as having absorbed an impressive number of shots for each goal conceded: Newport, Bradford and Forest Green are all currently in promotion contention despite the latter two allowing opponents a worrying number of chances. Meanwhile disappointing starts for Scunthorpe and Leyton Orient can be at least partly explained by leakiness at the back.

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:

When we adjust for shot quality, Forest Green stand out as an enigma: they are among the worst-looking of a clutch of seven poorly-performing sides here yet sit third in the table. The current top two of Swindon and Exeter look to have been the most impressive performers overall, with Crawley and Grimsby looking stronger in attack but relatively average at the back.