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Post by str8outtahampton on Jan 5, 2023 16:17:34 GMT
People completely under-estimate what a long term sample in football is. I’d argue that even a full season is prone to some wild deviations; hence my pushback against the cliche’ “the table never lies”. Roughly four whole repeated seasons to get most teams close to where their performance merits them to be. The table always lies for quite a few sides. I am struggling with the notion that the table lies (other than in circumstances where there is skulduggery to influence the outcome of games). However, I am prepared to be persuaded if there are examples of where it does lie.
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Post by PotterLog on Jan 5, 2023 16:20:43 GMT
People completely under-estimate what a long term sample in football is. I’d argue that even a full season is prone to some wild deviations; hence my pushback against the cliche’ “the table never lies”. Roughly four whole repeated seasons to get most teams close to where their performance merits them to be. The table always lies for quite a few sides. Can you clarify what you mean by "repeated seasons" here? You mean simulations of the exact same season with the same xG?
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Post by PotterLog on Jan 5, 2023 16:30:41 GMT
No need. All to need to know is previous xG predicts future goals better than previous goals does. The "All that matters is the result" mantra is wrong. The "xG is shite" brigade are wrong. There's no debate to be had. xG has won. Also tachyon.. as you seem to be around, can you give practical (or theoretical) examples of what you mean by your second line about predicting "future goals"? Over how long? A team or player's xG changes all the time so what period are we looking at to make a more accurate prediction (and predicting for how long)? Dunno if that lay talk makes sense, I'm just after more real-life evidence of how it "works" in the way you say.
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xG stats
Jan 5, 2023 16:57:54 GMT
via mobile
Post by mtrstudent on Jan 5, 2023 16:57:54 GMT
No need. All to need to know is previous xG predicts future goals better than previous goals does. The "All that matters is the result" mantra is wrong. The "xG is shite" brigade are wrong. There's no debate to be had. xG has won. Also tachyon.. as you seem to be around, can you give practical (or theoretical) examples of what you mean by your second line about predicting "future goals"? Over how long? A team or player's xG changes all the time so what period are we looking at to make a more accurate prediction (and predicting for how long)? Dunno if that lay talk makes sense, I'm just after more real-life evidence of how it "works" in the way you say. My guess/how I'd test it... Look at a bunch of teams (10?) who are scoring way under xG and the same who are scoring way over. Then look at whether they score more goals in their next 5 than they did in their last 5. I bet the first group on average sees increased scoring and the second group a decrease. Could put this on the table with some flutters on the sports betting!
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Post by Clayton Wood on Jan 5, 2023 18:44:59 GMT
No need. All to need to know is previous xG predicts future goals better than previous goals does. The "All that matters is the result" mantra is wrong. The "xG is shite" brigade are wrong. There's no debate to be had. xG has won. Do you make money out of this?
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xG stats
Jan 5, 2023 19:25:04 GMT
via mobile
Post by Gob Bluth on Jan 5, 2023 19:25:04 GMT
I’m always annoyed by our managers getting to the point where they tell us our xG is great and we’re just unlucky, usually followed by them telling us there’s nothing they can do and it’s down to the players. It’s as though their job is just to get us creating chances and not scoring them or they have no control over our stupid mistakes. Useless idiots.
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Post by nottsover60 on Jan 5, 2023 19:43:56 GMT
Neil does seem to be hot on with xG because he constantly references it in his interviews. To play devils advocate though I’m going to assume he’s persisted with Smallbone because he likes what he sees in terms of xG. That just doesn’t translate to what myself and many others (judging by the comments) see on the actual pitch which is that actually Smallbone isn’t very good. I don’t like smallbone either but it’s also possible he just has a great attitude and works hard in training and others don’t? As supporters we’re only ever privy to a snapshot of the full story; which is admittedly frustrating as hell. And does what he is tasked with doing on the pitch. As I said the other day on a different topic flying in with tackles isn't the greatest approach - that means a) you might overcommit and find yourself on your backside while the player and ball leave you for dead b) you risk giving away free kicks and picking up yellow cards c) a badly timed forceful tackle ends in a red card if you are late. Much better to get there and make the player with the ball do something to go past you. Leah Williams won the ball more times than any other player at the Women's World Cup but didn't put in a single tackle all tournament.
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Post by PotterLog on Jan 5, 2023 21:48:06 GMT
No need. All to need to know is previous xG predicts future goals better than previous goals does. The "All that matters is the result" mantra is wrong. The "xG is shite" brigade are wrong. There's no debate to be had. xG has won. Do you make money out of this? Tachyon’s said a few times s/he works in the field
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Post by tachyon on Jan 6, 2023 8:14:06 GMT
Roughly four whole repeated seasons to get most teams close to where their performance merits them to be. The table always lies for quite a few sides. I am struggling with the notion that the table lies (other than in circumstances where there is skulduggery to influence the outcome of games). However, I am prepared to be persuaded if there are examples of where it does lie. Teams get lucky. They sometimes winning lots of games by a single goal, sometimes these games turn into draws. With a bit of negative variance, draws turn into narrow losses. My fav example of a side that went on a prolonged hot streak, but without the underlying quality of process to sustain it was Reading in 16/17 when they finished 3rd & lost the playoff final in a pen shootout. Their goal diff was +4 (which wasn't great), they won 18 games and a playoff game by a single goal margin, but their expected goal difference was -16. Al-Habsi had a season that no keeper has had before or since. He wouldn't have repeated it even if he'd stayed. They were the 20th best side by xG in 2016/17, even though they finished 3rd. Next season they finished 20th.
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Post by tachyon on Jan 6, 2023 8:17:48 GMT
Roughly four whole repeated seasons to get most teams close to where their performance merits them to be. The table always lies for quite a few sides. Can you clarify what you mean by "repeated seasons" here? You mean simulations of the exact same season with the same xG? Just a season that has you playing a round robin schedule consisting of four home and four away games against the same side. So 184 total games for each team.
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Post by tachyon on Jan 6, 2023 8:54:48 GMT
Also tachyon.. as you seem to be around, can you give practical (or theoretical) examples of what you mean by your second line about predicting "future goals"? Over how long? A team or player's xG changes all the time so what period are we looking at to make a more accurate prediction (and predicting for how long)? Dunno if that lay talk makes sense, I'm just after more real-life evidence of how it "works" in the way you say. My guess/how I'd test it... Look at a bunch of teams (10?) who are scoring way under xG and the same who are scoring way over. Then look at whether they score more goals in their next 5 than they did in their last 5. I bet the first group on average sees increased scoring and the second group a decrease. Could put this on the table with some flutters on the sports betting! 30 teams who under perform their Championship xG most in a season, pretty much hit their xG in the following season. 30 teams who over perform their Championship xG in a season also pretty much hit their xG in the following season. Outcome regresses towards their underlying process. 5 games is unfortunately rife with statistical noise. Mean regression is long term. It's almost meaningless to talk about "clinical" or "non clinical" teams. You're almost always seeing random variation, not repeatable skill. If a team wants to do better it has to improve their underlying process(which xG measures), not rely on the transient trait of finishing that is way, way over valued as a factor.
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Post by pottersrule on Jan 6, 2023 9:02:47 GMT
Interesting overall stats but also interesting for the two recent homes games. 1.08 for Burnley and 1.83 for Preston. Thought from an attacking sense in both games we were dire. I imagine the Brown side foot in the first half and Delap "clearance" in the second half would've scored highly in xG terms so I think that's where 1.83 would've come from for the Preston game. But I do agree that attacking wise we were pretty shit. Haven't a clue where 1.08 has come from for the Burnley game though, their keeper didn't have a save to make and I can't remember a single chance of any note. One for tachyon because I'm interested as to where those numbers have come from. The Burnley keeper made a goal line save off Fox as I recall.Think that must be the one.
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Post by str8outtahampton on Jan 6, 2023 12:50:42 GMT
I am struggling with the notion that the table lies (other than in circumstances where there is skulduggery to influence the outcome of games). However, I am prepared to be persuaded if there are examples of where it does lie. Teams get lucky. They sometimes winning lots of games by a single goal, sometimes these games turn into draws. With a bit of negative variance, draws turn into narrow losses. My fav example of a side that went on a prolonged hot streak, but without the underlying quality of process to sustain it was Reading in 16/17 when they finished 3rd & lost the playoff final in a pen shootout. Their goal diff was +4 (which wasn't great), they won 18 games and a playoff game by a single goal margin, but their expected goal difference was -16. Al-Habsi had a season that no keeper has had before or since. He wouldn't have repeated it even if he'd stayed. They were the 20th best side by xG in 2016/17, even though they finished 3rd. Next season they finished 20th. I am not scoring points here, Mr(s) Tachyon, because whatever I might think, I accept that XGs is the currency of the day and your explanations are very helpful. However, whilst teams can of course get lucky, it doesn't follow that Reading finished where they did that season through luck. They might or might not have had a better than average slice of luck - I don't think it is possible to measure, let alone know. But it absolutely has nothing to do with luck that their keeper had such a terrific season. Nor does it follow that XGs was a reliable predictor for their following season. I guess I would warm to XGs more if there were a corresponding measure to reflect how effectively a team prevented goals. I suspect there must be such a thing. Is that how expected GD is measured? Meanwhile here's one for the youngsters - goal average, anyone?
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Post by PotterLog on Jan 6, 2023 15:26:49 GMT
Teams get lucky. They sometimes winning lots of games by a single goal, sometimes these games turn into draws. With a bit of negative variance, draws turn into narrow losses. My fav example of a side that went on a prolonged hot streak, but without the underlying quality of process to sustain it was Reading in 16/17 when they finished 3rd & lost the playoff final in a pen shootout. Their goal diff was +4 (which wasn't great), they won 18 games and a playoff game by a single goal margin, but their expected goal difference was -16. Al-Habsi had a season that no keeper has had before or since. He wouldn't have repeated it even if he'd stayed. They were the 20th best side by xG in 2016/17, even though they finished 3rd. Next season they finished 20th. I am not scoring points here, Mr(s) Tachyon, because whatever I might think, I accept that XGs is the currency of the day and your explanations are very helpful. However, whilst teams can of course get lucky, it doesn't follow that Reading finished where they did that season through luck. They might or might not have had a better than average slice of luck - I don't think it is possible to measure, let alone know. But it absolutely has nothing to do with luck that their keeper had such a terrific season. Nor does it follow that XGs was a reliable predictor for their following season. I guess I would warm to XGs more if there were a corresponding measure to reflect how effectively a team prevented goals. I suspect there must be such a thing. Is that how expected GD is measured? Meanwhile here's one for the youngsters - goal average, anyone? Yes there's xGA (xG against) which I suppose works the same way, although goalkeepers are apparently judged only on *post-shot* xGA. Isn't the whole point that it was basically "luck" - i.e. a prolonged run of positive variance in more or less random variables - that helped Reading that season? From what I understand about the goalkeeper, he outperformed even what you could expect from a top-class, in-form goalkeeper with a freak season that is basically impossible to repeat, i.e. he got lucky. (As well as generally playing well I'm sure)
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Post by str8outtahampton on Jan 6, 2023 16:33:31 GMT
I am not scoring points here, Mr(s) Tachyon, because whatever I might think, I accept that XGs is the currency of the day and your explanations are very helpful. However, whilst teams can of course get lucky, it doesn't follow that Reading finished where they did that season through luck. They might or might not have had a better than average slice of luck - I don't think it is possible to measure, let alone know. But it absolutely has nothing to do with luck that their keeper had such a terrific season. Nor does it follow that XGs was a reliable predictor for their following season. I guess I would warm to XGs more if there were a corresponding measure to reflect how effectively a team prevented goals. I suspect there must be such a thing. Is that how expected GD is measured? Meanwhile here's one for the youngsters - goal average, anyone? Yes there's xGA (xG against) which I suppose works the same way, although goalkeepers are apparently judged only on *post-shot* xGA. Isn't the whole point that it was basically "luck" - i.e. a prolonged run of positive variance in more or less random variables - that helped Reading that season? From what I understand about the goalkeeper, he outperformed even what you could expect from a top-class, in-form goalkeeper with a freak season that is basically impossible to repeat, i.e. he got lucky. (As well as generally playing well I'm sure) Well, "luck" isn't something that can be measured, and nor do I have any idea about what happened at Reading that season. But even if we could agree that the keeper's performance was lucky for them that season, you would (in order to conclude that they were lucky) have to factor in an almost infinite number of other variables. Injuries, refereeing decisions, suspensions, team harmony, fixture congestion - you name it. Reading might have benefited from more luck than any other side in the league - or they might not - it's simply not possible to say. My point was (badly expressed..!) that whilst a table can and often does lie at the start of a season, by the end it almost certainly doesn't. Reading probably deserved to finish 3rd because they finished 3rd.
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Post by tachyon on Jan 6, 2023 17:41:32 GMT
I am not scoring points here, Mr(s) Tachyon, because whatever I might think, I accept that XGs is the currency of the day and your explanations are very helpful.
However, whilst teams can of course get lucky, it doesn't follow that Reading finished where they did that season through luck. They might or might not have had a better than average slice of luck - I don't think it is possible to measure, let alone know. But it absolutely has nothing to do with luck that their keeper had such a terrific season. Nor does it follow that XGs was a reliable predictor for their following season.
I guess I would warm to XGs more if there were a corresponding measure to reflect how effectively a team prevented goals. I suspect there must be such a thing. Is that how expected GD is measured?
Meanwhile here's one for the youngsters - goal average, anyone?
[/quote][/b] Luck was probably a flippant term because it implies a lack of skill, which obviously isn't the case for any professional team or player. But the alternative term is "random variation centered around the true talent of a team or player". Which tends to check out any interest. Performance is a combination at true talent & random variation. Sometimes the latter is positive & helps a side & sometimes it's negative and hinders them. But it doesn't stick around, you have little control over it and all you can say is it is likely to become less extreme over time. (It's why you can flip a coin (true talent 0.5) and sometimes get a run of heads or tails. True talent is unchanged with a fair coin, but variance can run hot or cold at times. Al Habsi allowed 19 fewer goals than you would expect an average keeper to allow in 16/17....which was an insane level of over performance. The previous two seasons combined he allowed just one fewer than expected. He couldn't have done it without a huge slice of.....positive random variation. xG is a good guide to a player's true talent. Any over or under-performance is correlated to the team or player's positive or negative random variation (or luck). Reading's 16/17 season was the biggest outlier in the xG era (that's why I picked it), but every natural process (which includes football) is prone to random variation & every prediction is improved by accounting for its presence (along with a measure of true talent). The Championship is just a massive experiment in how randomness impinges on actual outcomes over a (short term) single season, where true talent is kept relatively stable, outside the three relegated sides and their parachute payments. Love the idea of bringing back goal average. Go for it!
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Post by str8outtahampton on Jan 6, 2023 18:06:13 GMT
LoL out extremely loud, tachyon!
I am an utter numpty on stats. However, I absolutely love the coin flipping reference. Even I get that.
And from now on, when I wish someone the best of fortune, I will shake their hand and say: "Good Positive Random Variation".
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Post by PotterLog on Jan 6, 2023 19:03:53 GMT
Yes there's xGA (xG against) which I suppose works the same way, although goalkeepers are apparently judged only on *post-shot* xGA. Isn't the whole point that it was basically "luck" - i.e. a prolonged run of positive variance in more or less random variables - that helped Reading that season? From what I understand about the goalkeeper, he outperformed even what you could expect from a top-class, in-form goalkeeper with a freak season that is basically impossible to repeat, i.e. he got lucky. (As well as generally playing well I'm sure) Well, "luck" isn't something that can be measured, and nor do I have any idea about what happened at Reading that season. But even if we could agree that the keeper's performance was lucky for them that season, you would (in order to conclude that they were lucky) have to factor in an almost infinite number of other variables. Injuries, refereeing decisions, suspensions, team harmony, fixture congestion - you name it. Reading might have benefited from more luck than any other side in the league - or they might not - it's simply not possible to say. My point was (badly expressed..!) that whilst a table can and often does lie at the start of a season, by the end it almost certainly doesn't. Reading probably deserved to finish 3rd because they finished 3rd. Well, what tachy is saying is that that's the perception, but not the reality.. one season, despite intuitions, is quite a short-term sample and the table can easily lie over that period. In fact if I'm reading it correctly if Reading's luck had fallen even slightly the other way they would have almost certainly gone down. Seems pretty extraordinary.
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