Saturday 29 July 2023

The Missing Ingredient

Ages ago, Opta used to have an OptaPro blog (I wrote the first article).

I also wrote a blog about trying to utilise how close (or not) off target goal attempts came to requiring a save.

It was called something like "Don't be afraid to miss" and centred around data relating to Robin van Persie. (It was that long ago).

The site has long gone, but with access to more extensive data, such as shot placement (including off target attempts), I've revisited the idea to see if the intuition that "good finishers", when they miss, don't miss by much, is valid or not.

The idea is fairly basic. A shot that hits the post, is inches away from being a high quality post shot xG, whereas one that flies high and wide is going to need a fair bit of resighting to trouble the keeper.

The metric will also be related to the situation from which the attempt originated (open play, free kicks- etc), where on the field it came from (six yard box, outside the box) and whether the head or the boot was used.

So I took every off target non penalty attempt from the big five league for the last three completed seasons (over 53,000) and modelled by how far a typical big five player missed the target with their wayward efforts based around these pre-shot variables.

I then compared the "expected waywardness" to the actual waywardness of individual players for every play type scenario.

I expected Messi to come top. He didn't. He came second out of over 3200 players, although he did have three times as many errant efforts than the player who beat him (Matteo Politano). So Messi's number are more robust.

Here's the top ten players whose off target attempts are close enough to elicit an "Ohh" from the crowd, along with the ten players whose misses gave the goalframe the widest berth.

The lists seem to pass the eye test. Messi, de Bruyne and Son in one list and Maupay and Havertz in the other.

I took the 30 top post shavers and looked at their NPxG compared to their actual goals and it was a cumulative 489 NPxG compared to 556 actual goals, an over-performance of 13.7%.

The worst 30 hopelessly wayward had a cumulative NPxG of 434.9, but just 394 actual goals scored. An under-performance of 9.4%.

Roughly 40% of goal attempts are retrieved by the ball boy/girl. But rather than discarding that sizeable chunk of data, there might be good reason to at last try to gather some insight from these wayward efforts.

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