Scatter graphics: National League, 2015/16 season

Now that the “regular season” is over in the National League, here are the final set of scatter graphics. These compare the attacking and defensive performance of each club: they are explained here if you haven’t seen them before and the previous instalment is 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).

NL Att Def 2016-05-01

Grimsby were the division’s most dominant side overall, but were ultimately unable to turn that dominance into a proportionate number of wins. While nobody took more shots than the Mariners, both Eastleigh and champions Cheltenham managed to restrict opponents to slightly fewer efforts at their goal.

Woking may have created plenty of chances but only relegated Altrincham allowed more in return: their defence looks to have collapsed in the last few months. The reverse is true of surprise play-off contenders Braintree, who took few shots but compensated by having one of the division’s most restrictive defences.

Another club who showed that you don’t have to take a lot of shots to do well were Gateshead, who took fewer than anyone else yet finished comfortably inside the top half.

Three of the four relegated clubs sit in the top left quadrant as you’d expect, but the fourth – Halifax – are in the top right, having created a respectable number of chances but ultimately being let down by their terrible defensive record earlier in the season.

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:

NL Att 2016-05-01

Again we have Grimsby in the bottom right: not only do they take the most shots but they’re among the more efficient finishers. Despite presenting a slightly larger all-round threat, Cheltenham weren’t the most clinical side in front of goal: that honour goes to Gateshead in the bottom left: their sharp shooting compensated for the lack of chances they created.

Tranmere can blame their wasteful finishing for not being able to emulate Cheltenham in making an immediate return to the Football League, and it also looks to have contributed to Halifax‘s relegation.

Relegated Welling were unfortunately the division’s least effective attackers by some distance in the top left, while Boreham Wood and Guiseley may also need some work up front if they’re to avoid the drop again next season.

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:

NL Def 2016-05-01

Cheltenham‘s impressive defensive record has stretched this graph out: it took over four more shots to score against them than the average side and only Eastleigh allowed opponents fewer opportunities to do so. Braintree are another side who can thank their defence for their impressively high league placing.

There are a cluster of four clubs in the top right quadrant who all allowed significantly more shots than the average but were better than most at soaking them up. The most surprising member of the quartet is Woking, who as I mentioned previously have seen their defensive performances plummet in the second half of the season.

In the bottom right we see the main culprit for Halifax‘s relegation: their defence was abysmal for much of the season and they ultimately left themselves with too much to do.

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:

NL EG 2016-05-01

Grimsby are once again lodged in the bottom right corner: when shots are corrected for quality they stand out as the division’s best all-round performers this season, so it’s a surprise to me that they didn’t give Cheltenham more of a run for their money.

Tranmere are another side who should probably have done better based on their overall performances, with Braintree‘s presence in the play-offs instead of them very surprising on this evidence. The Iron sit firmly in the bottom left, with a strong defence compensating for a relatively quiet attack. It’s great to have an unexpected promotion challenger last the distance and they’re no flat-track bullies – they only lost one of their matches against the rest of the top nine – but it will be interesting to see if they can keep overachieving like this.

In the top right, the relegation of Welling and Altrincham unfortunately look the least surprising as they were poor at both ends of the pitch, but Halifax didn’t look anywhere near as bad overall. If they can keep the bulk of their squad together then they should be in a strong position to make an immediate return.

Lincoln‘s attacking output was impressive this season – some modest improvements in defence could see them challenge for the play-offs next time around. Barrow also looked unusually threatening for a newly-promoted team.