Corner Count

Saturday 20^th October marked the 9-month anniversary (a whole football season in elapsed time) since Celtic last scored a goal direct from a corner kick pass. I know this is a bad stat as it includes the summer but I am feeding one of the great preconceptions here!

Since Boyata overshadowed the might of the Brechin City defence in the 56^th minute to score in a 5-0 walloping on 20^th January 2018, 279 corners have been taken without a goal DIRECT from the corner pass.

But that surely isn’t a problem in itself? Providing the pass into the box leads to a goal eventually. Since Brechin City, 3 goals have been scored in the phase of play subsequent to the corner:

• Dembele vs Greenock Morton, 3^rd March 2018

• Forrest vs Alashkert, 10^th July 2018

• Boyata vs Hamilton Academical, 26^th August 2018.

This is a goal resulting from 1% of corners taken. As I wrote about in Cutting Corners (I hope Celtic get better on corners for the single reason I’m running out of cheesy titles for articles about corners) a goal can be expected from a corner around 2.5% of the time. Not as often as most folk think, I’ll wager.

And whilst we’re about it, a shot resulting from a corner has a lower Expected Goals than is the same shot had been taken in regular play. This is because of the likely number of defenders in the way, and the relative structured readiness of the defence en masse.

Corner Performance Since 2017/18

But, swerving back on course, the overriding point is – YES, Celtic are getting poor returns from corners since January 2018.

Selecting a larger sample to get a better trend, the key numbers over the last two seasons (since start of 2017/18):

Of those 164 chances, 76 came from the corner kick pass and 88 from a second phase of action.

That works out at 6.75 corner per 90m and 2.02 chances per 90m from corners.

Comparing shot performance from corners versus open play shows that accuracy of shots is 10% lower than from open play. And conversion from all shots is 3% lower. This is not a surprise – as I mentioned, getting a shot following a corner usually means navigating a packed opposition box. Once Celtic do get a shot on target from a corner, the conversion rate is the same (1% higher) than from open play.

But the acid test of effectiveness is comparison versus two concepts you should now be familiar with:

1. Goals vs Expected Goals

2. Goals vs Industry Standard (2.5% of corners result in goals)

Goals vs Expected Goals

Celtic have scored 13 goals from their 547 corners since the start of last season.

If we add up the xG value of all the 164 chances created from corners, the comparison of goals vs xG is as follows:

Nearly 2 goals under performance since July 2017. Not a disaster but disappointingly below average.

Goals vs Industry Standard

Applying the 2.5% of corners result in goals observation to Celtic’s performance:

Again, Celtic have scored nearly 1 less goal from corners that the industry standard would suggest. But on the upside Celtic are creating slightly better-quality chances than “normal”. An extra 1 or 2 goals would likely see Celtic slightly “above average”.

Conclusion

Performances at corners is one of the football fan sacred cows like zonal marking and playing two up front. The reality is Celtic are a bit mediocre at corners, and to be critical, a bit below average since the start of the 2017/18. But not disastrously so.

However, since January 2018, the performance from corners has been woeful with only 1% of corners resulting in goals even though performance in the full period under analysis is slightly below average at worst.

Statistical blip, or systematic issue?

Ideas in the comments section please on how to answer that!