But the point is: It doesn't measure that reliably yet.
xG values were originally attributed simply to the position from where a shot was taken.
Over the years a few more factors were put in. 1on1s, headers or weak foot strong foot were added and inconsistently applied.
But too many factors are still not present in current xG evaluation
- individual ability
- how much time does the shooter have
- how much space does the shooter have
- where is the goalie positioned (here back to the Lewy example: Goalkeeper lies flat on the ground, unable to do anything except of hoping to be shot at, then Berisha on the other hand shooting from the SAME position, but against an upright standing Neuer who closed him to less than a meter. And still Berisha had a slightly HIGHER xG for his chance than Lewandowski had)
- were are defenders positioned (inbetween scorer and shot? Close enough to pressure the shooter?)
- does the shooter fully control the ball or not
etc.
There was a very decent article written about this over a year ago evidenced through the game Leicester-Wolverhampton
https://thevideoscope.com/2019/08/13...ardy-jota-fpl/
Last edited by Yannik; 26th November 2020 at 10:21 PM.
Yeah Im aware, in general the further away you are, the harder it is for an average striker to get it on target & score.
It most likely never will involve individual ability because it varies over time with hundreds of players depending on form.But too many factors are still not present in current xG evaluation
- individual ability
Nor should the value vary depending on who's on the end of it IMO. You're only assessing whether a striker 'should' score irrespective of talent. Not whether an elite one will be more likely to do so against a shit keeper.
Would be nice to have. Pretty sure there is some manual adjustment on the end of stat producers. But I dont know for sure.- how much time does the shooter have
- how much space does the shooter have
So why is xG lower? We're kind of debating here as to what goes into and what doesn't, but do you know what actually made it lower? Because from the sounds of it you're just miffed by the value because Lewa scores these in his sleep.(here back to the Lewy example: Goalkeeper lies flat on the ground, unable to do anything except of hoping to be shot at, then Berisha on the other hand shooting from the SAME position, but against an upright standing Neuer who closed him to less than a meter. And still Berisha had a slightly HIGHER xG for his chance than Lewandowski had)
People are boring.
Yes, Lewandowskis shot was 6m out Berishas was 5m out, so it was valued higher as explained above.
But the fact that Lewandowski practically just tapped it home against a goalkeeper lying flat on the floor - whereas Berisha had Neuer stretching practically 10cm before him - is not a factor considered in the current algorithm.
Last edited by Yannik; 26th November 2020 at 11:05 PM.
Apart from individual ability, all the rest have started being incorporated gradually.
Many models even today account for space, position of the goalie, position of defenders.
I guess the time the shooter has, the speed of the pass before shooting, the full control of the ball will be the last to get incorporated (they are the most difficult to account for)
Your point about individual ability still stands, but I think it's not science fiction to say that with the algorithm learning techniques that already exist, in the near future the models will be able to: track the record of a certain player and measure his effectiveness from all different positions (and in regards to all the factors you mention) and 'learn' the value to be assigned to each player individually (instead of the generic one).
Form is a factor, but these models (when they arrive) will be 'learning' constantly and thus adjusting continuously the relevant value.
IMO, it would be interesting to see for a given game both the 'should' according to generic values, and the 'should' according to individuated values.
PS: The article you shared focuses on the preparatory stages before a play gets converted into a chance. This is not supposed to be captured by xGs but other sophisticated stats
Last edited by Birdy; 27th November 2020 at 01:32 AM.
Modric 7th start in 3 weeks. Wtf Zidane
People are boring.
Dreadful pass from Nacho.
Varane looks half the player he once was. Will be interesting to see if he can recover his game.
Called it![]()
classic varane
Barca will win the league, trust me.
Edit (after 2-1 loss against Cadiz): Don't trust me.
Edit2 (after 1-1 against Eibar): Its over guys.
Edit3 (after Real 1-1 against Elche): Congratulations Atletico.
LMAO Varane.
The guy is a fucking walking disaster everytime Ramos doesn't play.
Valverde: "I don't think about resigning and I don't feel like players have failed me."
Valverde: "This is football. It costs us and it costs the whole world."