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Post by tachyon on Jan 25, 2020 10:03:34 GMT
A couple of active threads related to football analytics, so I've put together some metrics that are commonplace for those who might be interested. Not exhaustive, but I'll perhaps add others.
xG (expected goals). Chance quality based on where and how an attempt is taken from. Can include other factors. An xG of 0.8 is expected to be scored 8 times out of 10. Shots from the edge of the box have a lower xG than shots from the edge of the six yard box.
***** 5 star stat, invaluable at team & player level.
xG2 (post shot expected goals) What happens after the shot. Is it powerfully struck with swerve and dip or does it trundle along the ground towards the middle of the goal. Shot that misses the target has xG2 of zero, shot that pings towards the top corner from three yards out has around 0.9.
***** 5 star, but best used descriptively as it is much more prone to variance than xG.
Non shot xG. Whether a pass or carry improves your chances of scoring. Square balls in your own half add little or nothing, through balls into the box add a lot. Can also be used for ball retention (backward passes that keep possession) or errors (intercepted passes or missed tackles that allow an opponent to advance the ball).
***** 5 star.
PPDA (passes allowed per defensive action).
Catchy name and has been superseded by non shot models. Measures ball retention or pressing. If you’re allowing lots of passes before you get a foot in, the inference is you aren’t actively seeking to regain the ball.
*** 3 star Great insight at the time (2014)
Tracking data. Where all 22 players are on the pitch in real time. Cool state of the art addition to xG models. Shows which part of the field each player controls (basically where they can run to before anyone else on the field can get there).
Takes longer than the game lasts to process the data.
***** 5 star. Credits off the ball runs to create space. Looks at which options were taken and whether better ones existed.
Age curves. Players get better, peak and then decline. Peak age years are between around 24 and 29, although positions are slightly different. Great way of seeing how well a squad is assembled or if it’s in need of fresh blood.
***** 5 star.
xChain & xBuildup.
If a player gets on the end of a good chance (xG 0.7 say) every player who was involved in the passing movement is credited with that 0.7 xG, even if they just passed the ball two yards inside their own half.
No stars. Crazy that this ever got out. The flaws are obvious, but it’s become the go to method to “prove” that VvD is more creative than KdB. Trivia, nothing more. Ignore.
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Post by FullerMagic on Jan 26, 2020 9:24:04 GMT
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