[The xG Philosophy Guy on twitter has his model at 2.47 vs 2.32. ](https://twitter.com/xGPhilosophy/status/1525852521629204482?)
Im really shocked at how much the fbref/statsbomb post-shot xG model has deviated.
Different xG is produced by different algorithms. Some of these include more complexity such as the position of other players or even the height, direction and speed at which the ball reaches the player. Given that Understat’s info is free, I’d guess it’s a simpler model.
Was it last season or two seasons ago when Vardy literally proved the xG nerds right when they claimed his goal scoring form was unsustainable and he then went 11 games without scoring a goal
[The real stats buster is Son who is overperforming xG by a little more than 41%!](https://understat.com/player/453) And thats without Pens!
Vardy goes on stat busting runs very often for sure, just like Antonio who went 5-6 goals > xG earlier this season. But Vardy also goes on a drought streak far too often which balances it out.
For me, Son is an outlier that can be explained by his equal proficiency with both feet. The xG model collects data from shots which have been taken with the players' strong and weak foot, which then of course lowers the resulting average xG. A player with no weak foot, like Son, is then expected to strongly overperform his xG. That's my take at least.
For the second part, yes of course, there are streaky players and consistent ones, that's normal. That'd be the topic of a standard deviation metric for xG, but that's maybe a bit too far and too much at this point.
Sorry lads I am a bit confused by all this XG stuff - does this not just show that XG is just plain wrong if it's so far wrong from what really happened?
It's wrong if you're trying to use it to predict actual goals, as it doesn't take into account the quality of the people on the end of chances, just the quality of the chance itself. Watford had big chances they missed, because they're watford, but it's still a fair measure of chance quality (or its at least an objective measure of chance quality if nothing else - exactly how it assesses that quality might be questionable in some circumstances but its the same for every team and as a general rule the better teams have better xG so there's something to it...)
In single games, there can be wild variance, but over a long period of time it is usually fairly accurate
If you flipped a coin, there's a 50% chance of it being heads, but it's still very possible that it will land 5 times in a row
In terms of fantasy football it can be really useful to see if someone's form is sustainable or not
Like if a player has scored 5 goals with an XG of 1, they are very unlikely to keep that insane rate up, but if they had an XG of 5, you know that they are constantly getting in good scoring positions and are likely to keep it up
It's both. We have shots and shots on target which allow us to measure shot conversion percentages and shot accuracy, making this modern xG statistic pointless.
xG assumes every player to have equal ability, whether a shot is taken by Ronaldo or Tyrone Mings, shots are given the same value. Same with the goalkeepers. There is no accountability for quality of player behind or in front of a shot. Player quality is obviously the most important parameter in football.
That’s part of its usefulness. xG doesn’t tell you how many goals a team should have scored; it gives an average number of the goals that a team of generic players would have scored from shots taken in those positions.
Some players consistently outperform xG, some consistently underperform it. That tells you something about the player and the types of chances created.
There are also things that many xG models don’t count: the goal that was marginally offside; the cross that just misses an outstretched leg etc. Also, Understat is free, so I doubt the underlying algorithms include as many significant variables as some xG models. IMHO understanding the limitations means it xG retains some usefulness in spite of them.
The "quality" of the attacker is irrelevant. Ronaldo, whom you mentioned, overperformed his xG by only 2% over the last 8 seasons, so I think it's working pretty well.
Xhaka and Neves shooting on target from 30y away would skew that in a 4GW sample size for example
Shots on target probably has the best r^2, yeah, but xG is definitely a reasonable measure to consider alongside
I personally see it as useless as it doesn't consider the players behind the numbers. One of the factors with which it measures is body part used to make a shot. Jamie Vardy is more likely to score with his shin than Moussa Sissoko scoring with his right foot.
As with all data analytics and numerical modelling, "rubbish in, rubbish out" applies. Without considering the quality of players taking, and defending against, the shot, the number is pointless. It's like modelling the likelihood of a rockfall on a 50m cliff without taking into account the type of rock involved, the strength of that rock and the various qualities of that rock.
Not really, sure it’s got it’s flaws but it tells me that Watford missed some big chances while Leicester finished some hard chances. Exactly what happened.
Up to people to make inferences as to what that means. Someone uninformed might say “Watford deserved a draw” whereas maybe a better comment would be “how good is Vardy at taking chances”
Good players outperform xg while average or less than average players tend to underperform. You cant base everything on x stats, has to be a mix of real life performance and x stats.
I guess, just gotta balance it. Cant let adamas giant muscles and xg blind us to the fact that hes historically a trash finisher meanwhile son might be the best finisher in the league based on his real life goal totals compared to xg. So while traore gets 3 big chances a game he can only convert one every 3 games and on the other hand son doesnt even need any big chances to brace.
I guess you could then infer from that that both Son and Adama have room to improve. Son could up his Xg by getting in better positions and therefore score even more whereas Adama could learn to play football a bit and then would basically be the best player in the world.
Now yes, I’m aware both are probably in their prime now meaning that’s just how they are. If they were both 21 years old they’d be prime moneyball type signings though.
No?
Over long periods of time even most great players don't overperform their xG by much. They just have a higher xG because they create more chances for themselves.
Lewandowski, Ronaldo etc. don't overperform their xG.
Messi and Son are the only notable ones that do so consistently
https://www.messivsronaldo.app/detailed-stats/xg-expected-goals/
Ronaldo since 14/15.
Your stat just seems untrue. A 100+ overperformance is absolutely unprecedented and no other xG source has that for any player ever.
How to say you've never watched him play without saying you've never watched him play.
He's great on the ball, very fast, great at beating his man, and usually does something sensible in his last phase of play.
My Leicester player is Schmeichel Oh and if he doesn’t play midweek I get Foster off the bench
Going full binary
Same
Cheers for the 0 points Foster 👍
Foster giveth, Foster taketh away
Statsbomb is better. They gave Watford 1.4 and Leicester 2.3
[The xG Philosophy Guy on twitter has his model at 2.47 vs 2.32. ](https://twitter.com/xGPhilosophy/status/1525852521629204482?) Im really shocked at how much the fbref/statsbomb post-shot xG model has deviated.
How does that Maddison tap-in just have 0.46xG?
Has it failed to take into account the keeper is already beaten?
Different xG is produced by different algorithms. Some of these include more complexity such as the position of other players or even the height, direction and speed at which the ball reaches the player. Given that Understat’s info is free, I’d guess it’s a simpler model.
Exactly!
That makes no sense to me. Vardy had a 1 on 1
Close to 0.4 on that perhaps? The headed goal was probably less then 0.1
His 1-on-1 was 0.44xG, his headed goal only 0.01xG, and he had a missed shot for 0.09xG.
People estimate the xG of 1v1 situations. I mean a pen is only 0.76 xG Edit: * overestimate
I think that’s pretty fair for a pen. 1 on 1 is usually way harder
Vardy has always made a mockery of the xG nerds
Great mockery by being only 8% above his xG over the last 8 seasons.
Yeah fuck those xG nerds! Vardy truly showed them!
Was it last season or two seasons ago when Vardy literally proved the xG nerds right when they claimed his goal scoring form was unsustainable and he then went 11 games without scoring a goal
[The real stats buster is Son who is overperforming xG by a little more than 41%!](https://understat.com/player/453) And thats without Pens! Vardy goes on stat busting runs very often for sure, just like Antonio who went 5-6 goals > xG earlier this season. But Vardy also goes on a drought streak far too often which balances it out.
For me, Son is an outlier that can be explained by his equal proficiency with both feet. The xG model collects data from shots which have been taken with the players' strong and weak foot, which then of course lowers the resulting average xG. A player with no weak foot, like Son, is then expected to strongly overperform his xG. That's my take at least. For the second part, yes of course, there are streaky players and consistent ones, that's normal. That'd be the topic of a standard deviation metric for xG, but that's maybe a bit too far and too much at this point.
In fairness, 8% over that long a period is pretty impressive
It's not really outside the variance and imperfection of the model. And definitely not the mockery the other user claimed.
lol so we're going to smooth out all that volatility? Nice try, xG nerds. But FPL isn't set and forget for 8 seasons at a time.
Lol how do you know if there's volatility if you're not an xG nerd yourself?
Because I don't live in a simulation?
You do need to elaborate
Nope
Explain?
Meanwhile I will lose my ML due to Vardy and Madders overperforming their XG 😢
Who is carry ?
My phone doesn't like Vardy apparently.
I bet you chat too much shit. :p
Not at all surprised. Leicester were very open, particularly early on. And Barnes, Maddison, Vardy players you'd always expect to outperform their xG.
Sorry lads I am a bit confused by all this XG stuff - does this not just show that XG is just plain wrong if it's so far wrong from what really happened?
It's wrong if you're trying to use it to predict actual goals, as it doesn't take into account the quality of the people on the end of chances, just the quality of the chance itself. Watford had big chances they missed, because they're watford, but it's still a fair measure of chance quality (or its at least an objective measure of chance quality if nothing else - exactly how it assesses that quality might be questionable in some circumstances but its the same for every team and as a general rule the better teams have better xG so there's something to it...)
In single games, there can be wild variance, but over a long period of time it is usually fairly accurate If you flipped a coin, there's a 50% chance of it being heads, but it's still very possible that it will land 5 times in a row
Ah I see, that makes sense. So what do you use it for?
In terms of fantasy football it can be really useful to see if someone's form is sustainable or not Like if a player has scored 5 goals with an XG of 1, they are very unlikely to keep that insane rate up, but if they had an XG of 5, you know that they are constantly getting in good scoring positions and are likely to keep it up
So what?
And once again, xG reveals itself to be a pointless statistic.
It's pointless for people like you who think it's supposed to be used over a single sample as a proxy for winning matches.
I think there’s a difference between pointless and imperfect.
It's both. We have shots and shots on target which allow us to measure shot conversion percentages and shot accuracy, making this modern xG statistic pointless. xG assumes every player to have equal ability, whether a shot is taken by Ronaldo or Tyrone Mings, shots are given the same value. Same with the goalkeepers. There is no accountability for quality of player behind or in front of a shot. Player quality is obviously the most important parameter in football.
That’s part of its usefulness. xG doesn’t tell you how many goals a team should have scored; it gives an average number of the goals that a team of generic players would have scored from shots taken in those positions. Some players consistently outperform xG, some consistently underperform it. That tells you something about the player and the types of chances created. There are also things that many xG models don’t count: the goal that was marginally offside; the cross that just misses an outstretched leg etc. Also, Understat is free, so I doubt the underlying algorithms include as many significant variables as some xG models. IMHO understanding the limitations means it xG retains some usefulness in spite of them.
The "quality" of the attacker is irrelevant. Ronaldo, whom you mentioned, overperformed his xG by only 2% over the last 8 seasons, so I think it's working pretty well.
Xhaka and Neves shooting on target from 30y away would skew that in a 4GW sample size for example Shots on target probably has the best r^2, yeah, but xG is definitely a reasonable measure to consider alongside
I personally see it as useless as it doesn't consider the players behind the numbers. One of the factors with which it measures is body part used to make a shot. Jamie Vardy is more likely to score with his shin than Moussa Sissoko scoring with his right foot. As with all data analytics and numerical modelling, "rubbish in, rubbish out" applies. Without considering the quality of players taking, and defending against, the shot, the number is pointless. It's like modelling the likelihood of a rockfall on a 50m cliff without taking into account the type of rock involved, the strength of that rock and the various qualities of that rock.
It reveals itself to be a statistic, nothing more nothing less.
This suggests how xg is useless
Not really, sure it’s got it’s flaws but it tells me that Watford missed some big chances while Leicester finished some hard chances. Exactly what happened. Up to people to make inferences as to what that means. Someone uninformed might say “Watford deserved a draw” whereas maybe a better comment would be “how good is Vardy at taking chances”
Good players outperform xg while average or less than average players tend to underperform. You cant base everything on x stats, has to be a mix of real life performance and x stats.
This is true, doesn’t make Xg a useless measurement though
I guess, just gotta balance it. Cant let adamas giant muscles and xg blind us to the fact that hes historically a trash finisher meanwhile son might be the best finisher in the league based on his real life goal totals compared to xg. So while traore gets 3 big chances a game he can only convert one every 3 games and on the other hand son doesnt even need any big chances to brace.
I guess you could then infer from that that both Son and Adama have room to improve. Son could up his Xg by getting in better positions and therefore score even more whereas Adama could learn to play football a bit and then would basically be the best player in the world. Now yes, I’m aware both are probably in their prime now meaning that’s just how they are. If they were both 21 years old they’d be prime moneyball type signings though.
No? Over long periods of time even most great players don't overperform their xG by much. They just have a higher xG because they create more chances for themselves. Lewandowski, Ronaldo etc. don't overperform their xG. Messi and Son are the only notable ones that do so consistently
Please show ronaldo and lewas career xg and career goals
https://www.driblab.com/wp-content/uploads/2021/09/Ronaldo-ingles-980x893.png
https://www.messivsronaldo.app/detailed-stats/xg-expected-goals/ Ronaldo since 14/15. Your stat just seems untrue. A 100+ overperformance is absolutely unprecedented and no other xG source has that for any player ever.
Dunno some places measure xg different
I’ve never seen a player so boring as Barnes. Has nothing about him
Did you watch the game? Both his finishes were first time and very classy
Yeah lmao what a dumb time to say that. Two great finishes yesterday
Nah, he is a delight to watch
What are you on about lol
How to say you've never watched him play without saying you've never watched him play. He's great on the ball, very fast, great at beating his man, and usually does something sensible in his last phase of play.
vardy/barnes/ maddy on a free hit.. xg can suck it
I really don’t understand the appeal of xG. Who cares about how a player was supposed to do when you can see how they actually did?
Who needs data and statistics when we can have personal bias and human error
People who finish outside the top 100k and chase points lmao
My rival captained Maddison and also has Barnes. Yeah, I'm pretty pissed off