| I still don't understand xG - plus Delap and Enciso 11:45 - Jan 23 with 3214 views | GavTWTD |
Is there one xG calculation? I feel that xG is based on circumstances and therefore opinion on what circumstances to include, so could I come up with my own xG?
I don't understand Delap's figures (from whoscored):
Tournament Apps Mins xG Goals xGDiff xG/90 Shots xG/Shots Rating
Premier League 20(1) 1614 8.43 8 -0.43 0.47 37 0.23 6.71
Ok so his xG per 90 is easily calculated.
His xG is 8.43. What's that mean?
xG Diff is -0.43 What's that mean?
xG/shot I assume is easily worked out if you know how many shots he's made but I've not attempted to work it out.
Enciso
Premier League 2(10) 288 1.16 - -1.16 0.36 20 0.06 6.37
His figures don't look good in comparison but he's not a striker and not played many mins. I just thought it would be interesting to include as he's just signed. |  |
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| Reading a great book on this, XG explainer - How to Win Premier League? on 14:53 - Jan 23 with 188 views | Marshalls_Mullet |
| Reading a great book on this, XG explainer - How to Win Premier League? on 13:59 - Jan 23 by unstableblue |
From the Liverpool stats guru - who identified all those good players, managers
He's very good - interestingly he sights Brentford and Brighton as the only clubs close to Liverpool's model, not Man U, or Chelsea.
Need to pinch some of these methods.
Simplistically he calls XG - "Weighted Shots" - which is a much better explanation, and brings out the flaws in the metric.
So XG is "Expected goals (xG) measures the quality of a shot based on several variables such as assist type, shot angle and DISTANCE FROM GOAL, whether it was a headed shot and whether it was defined as a big chance" (another source)
What are the flaws of xG?
"Its reliability diminishes significantly when used for single games or individual shots, where context and variance play a much larger role. it often shows unreliable Interpretation with small data. " (another source)
Penalty high XG, shots from edge of box despite being a blaster and on target and really testing keeper do not all get 'clear cut chance' in the stats, hence low XG. We had 4 pretty good efforts first half against City - agree some shoudl be low XG, maybe two higher, assume only Omaris which was flicked over got high XG.
So Gav your own XG would perhaps be more sophisticated in rating a shot for likelihood of a goal, say difficulty of save a shot produced for keeper by some some scale - but this would be too hard to do quickly. So XG is effectively done on all the shots from the D for example how may go in, not the specific shot in question.
That's not the major theme of the book - its brilliant to read the recruitment, players no one in Europe was up for - Matip a good example - he was failing all the measure of other teams. But they measured in a different way, picked him up, got some very important performances out of him. |
I think Brighton and Brentford were at it before Liverpool. |  |
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