Xg - is it a load of bo***x

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Argentinemanager said:
Just looked on a couple of sites and our expecred goals for yesterdays game were 1.7 and 2.1, both equating to a 2-0 victory, as i watched the game i thought we should have had about 5, so is this xg a load of bo***x
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It's all about probability of scoring from the position you're in etc. The Thiago goal in the Champions League other night for example. That wasn't an expected goal situation. He had no right to score from that position:



Here's more of an explanation

https://fbref.com/en/expected-goals-model-explained/
 
Whilst xG is a useful indicator of the overall quality of chances, I wouldn't say it's completely infallible, or always representative of an overall match.
That said, given your example where the xG was in line with what the score actually ended up being, I don't see what the immediate problem is.
 
Argentinemanager said:
Just looked on a couple of sites and our expecred goals for yesterdays game were 1.7 and 2.1, both equating to a 2-0 victory, as i watched the game i thought we should have had about 5, so is this xg a load of bo***x
Click to expand...
I was trying to explain it to my son last night and I noticed that the chance missed by Brewster early doors doesn't get assigned xG because he didn't connect with the ball. He was 2 yards out in the centre of the goal so I'm assuming it would have been similar to the 65% from Sharp's goal or probably even higher.
 
Argentinemanager said:
Just looked on a couple of sites and our expecred goals for yesterdays game were 1.7 and 2.1, both equating to a 2-0 victory, as i watched the game i thought we should have had about 5, so is this xg a load of bo***x
Click to expand...
"The xg matched the result perfectly, therefore it's a load of bollocks". 😂
 
I actually really rate it and think it usually tells the story. Whilst we do get ourselves in good positions we often don't carve out a clear goalscoring opportunity for ourselves. We're not missing sitter after sitter. If our XG sat somewhere around 2 - 2.5 yesterday then I'd say that's about right (hadn't appreciated Brewster's wouldn't register as per above post). Bristol's probably should have been around 0.5 at a guess.
 
derekacorah said:
I was trying to explain it to my son last night and I noticed that the chance missed by Brewster early doors doesn't get assigned xG because he didn't connect with the ball. He was 2 yards out in the centre of the goal so I'm assuming it would have been similar to the 65% from Sharp's goal or probably even higher.
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Not 100% sure what XG is or about, personally prefer the old fashion way of , bums off seats, tells your more about a game than anything else I've come across.
Adkins era, bums off seats happened 3 times in a full season, and that was spot on analysis. 🤣
 
We are 5th in the OVERALL xG table with 1.51 and 4th in the HOME xG table with 1.74.

We've played 20 games so 20 x 1.51 should be 30 goals scored. We've actually scored 25. In home games we should have scored 17 goals and have only scored 15. This means we're not converting the clear cut chances as much as we should have.

xGA (Expected Goals Against) - United are 20th (this is good) with an xGA of 1.13 which suggests we should have conceded 22/23 goals. We've conceded 26.

Simply put we're not taking the chances upfront and are conceding when we shouldn't be. We're 5th in xG and 5th best (20th) in xGA yet we're down in 13th position.

Interestingly, Bournemouth's overall xG is 1.36 which suggests they should have scored 27 goals so far. They've actually scored 36 which means they're outperforming.

Here's the xG table:

1638184183914.png
 
It’s an indicator of chances created, but watching yesterday we should’ve scored more than we did easily.
 
mattbianco1 said:
We are 5th in the OVERALL xG table with 1.51 and 4th in the HOME xG table with 1.74.

We've played 20 games so 20 x 1.51 should be 30 goals scored. We've actually scored 25. In home games we should have scored 17 goals and have only scored 15. This means we're not converting the clear cut chances as much as we should have.

xGA (Expected Goals Against) - United are 20th (this is good) with an xGA of 1.13 which suggests we should have conceded 22/23 goals. We've conceded 26.

Simply put we're not taking the chances upfront and are conceding when we shouldn't be. We're 5th in xG and 5th best (20th) in xGA yet we're down in 13th position.

Interestingly, Bournemouth's overall xG is 1.36 which suggests they should have scored 27 goals so far. They've actually scored 36 which means they're outperforming.

Here's the xG table:

View attachment 125592
Click to expand...
This is what I was explaining yesterday, then got into the debate around how we create more with McGoldrick on the pitch but probably lose out on actual goals v xG when a chance falls to him, like a double edged sword of having a great creative player who probably should be on 3 more goals than he has scored for the season himself as well.

I do enjoy stuff like this but then sometimes the data gives you false impressions of the games we've played. Possession stats at least seem to be a thing of the past in terms of a yardstick for a good performance as proven by us this season.
 
derekacorah said:
This is what I was explaining yesterday, then got into the debate around how we create more with McGoldrick on the pitch but probably lose out on actual goals v xG when a chance falls to him, like a double edged sword of having a great creative player who probably should be on 3 more goals than he has scored for the season himself as well.

I do enjoy stuff like this but then sometimes the data gives you false impressions of the games we've played. Possession stats at least seem to be a thing of the past in terms of a yardstick for a good performance as proven by us this season.
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Yeah, the 2 chances he had against Coventry as a prime example. Not sure what they were rated at but i'd say 0.8/0.9 chances
 
Shoreham_Bhoys said:
It’s an indicator of chances created, but watching yesterday we should’ve scored more than we did easily.
Click to expand...

In fairness to City they did get in four or five blocks which seemed like a large number, I assume most xG models will account for how clear a shot a player has but that seems to be above expectation which won't necessarily show up on a simple xG figure
 
mattbianco1 said:
We are 5th in the OVERALL xG table with 1.51 and 4th in the HOME xG table with 1.74.

We've played 20 games so 20 x 1.51 should be 30 goals scored. We've actually scored 25. In home games we should have scored 17 goals and have only scored 15. This means we're not converting the clear cut chances as much as we should have.

xGA (Expected Goals Against) - United are 20th (this is good) with an xGA of 1.13 which suggests we should have conceded 22/23 goals. We've conceded 26.

Simply put we're not taking the chances upfront and are conceding when we shouldn't be. We're 5th in xG and 5th best (20th) in xGA yet we're down in 13th position.

Interestingly, Bournemouth's overall xG is 1.36 which suggests they should have scored 27 goals so far. They've actually scored 36 which means they're outperforming.

Here's the xG table:

View attachment 125592
Click to expand...

I'd be intrigued to see Billy Sharp's XG stats this season. I feel like he's missed 3 or 4 really good chances.
 



jt64 said:
Sharp is about 1.5 xG above what he's actually scored per infogol, although half of that will be the penalty miss v Hull
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Fair. Maybe my expectations of him outweigh what an average player should be able to do.
 
Shoreham_Bhoys said:
It’s an indicator of chances created, but watching yesterday we should’ve scored more than we did easily.
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Xg doesn't record how many goals we should have scored had our players turned up in top form, it measures how many goals Championship players were likely to score given the chances. It was spot on.
 
mattbianco1 said:
Yeah, the 2 chances he had against Coventry as a prime example. Not sure what they were rated at but i'd say 0.8/0.9 chances
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It's a valid point but viewers tend to overrate chances, in terms of thinking they are easier than they actually are.

For example, penalties have a fixed xG of around 0.78, which means 78 out of every 100 are scored. Fans will never excuse a penalty being missed, but over 20% are.

The only example of a 1.0 I've ever seen was McBurnie's goal for Barnsley against us in 2018.

Our two highest xG moments v Coventry both fell to McGoldrick (0.31 and 0.26).
 
It's all a load of wank mate. Stats based analysis is useful for spotting patterns if you've a big weakness etc but in sports that have used it heavily (particularly cricket) it's already reached it's peak and will tail off...(most) sports are spontaneous and rely on improvisation and skill. The stats stuff is too prescribed and will have soon had it's day.
 
raimond said:
It's all a load of wank mate. Stats based analysis is useful for spotting patterns if you've a big weakness etc but in sports that have used it heavily (particularly cricket) it's already reached it's peak and will tail off...(most) sports are spontaneous and rely on improvisation and skill. The stats stuff is too prescribed and will have soon had it's day.
Click to expand...

I'm sure you'd argue that you can tell McGoldrick might need to work on his finishing based on an eye test rather than actual data, but being able to look behind just the league table and actually use data to quantify how lucky/unlucky a team has been and/or being able to identify areas of the pitch that are strengths and weaknesses is kind of important
 
raimond said:
It's all a load of wank mate. Stats based analysis is useful for spotting patterns if you've a big weakness etc but in sports that have used it heavily (particularly cricket) it's already reached it's peak and will tail off...(most) sports are spontaneous and rely on improvisation and skill. The stats stuff is too prescribed and will have soon had it's day.
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It’s just one more tool that has to be used correctly.

Not sure if your comment about spontaneity and improvisation suggests that you aren’t a fan of planning and preparing too. Are you?

Anything that gives an edge is worth taking into account.
 
raimond said:
It's all a load of wank mate. Stats based analysis is useful for spotting patterns if you've a big weakness etc but in sports that have used it heavily (particularly cricket) it's already reached it's peak and will tail off...(most) sports are spontaneous and rely on improvisation and skill. The stats stuff is too prescribed and will have soon had it's day.
Click to expand...
Elite sport is about fine margins, not big weaknesses.

xG isn't perfect but it's a very decent way of measuring how good a player is in those spontaneous moments you mention, which can then be looked at across a whole team.

It's hated because it proves people's gut instinct wrong. Not many people like being wrong and even fewer like to challenge their own instinct.

I think the name "expected" throws people off. It's nothing to do with prediction. A shot with an xG of 0.5 simply means if it happened 100 times you would "expect" to see a goal scored in 50.

Spotting a player who outperforms their xG is a huge part of scouting an attacking player. If they do it consistently, they're world class.

It can also be used for other purposes, ie if a player keeps shooting from low xG opportunities he shouldn't be shooting as often.

Possession was the new trendy stat in the 90s, but it doesn't mean everything. Shots on target is another indicator of how a game panned out. xG is merely another. Others you'll start to see more: PPDA - passes per defensive action. This is an indicator of how long a team allows their opponents to keep the ball, ie how many passes they allow to happen before trying to tackle or intercept. That can also indicate how high a team chooses to press their opponents.

Anyone who has ever said "he should have scored from there" or "we should've won 5-0" is interested in xG whether they realise it or not.
 
PaniniBlade said:
"we should've won 5-0"
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xG proves that there are very few occasions when this sentence is true - often you "should" have won 3-0 - but overperformed slightly.

Case in point - we beat Peterborough 6-2 - the xG had that as closer to 3-2 on the strength of chances created.
 
Argentinemanager said:
Just looked on a couple of sites and our expecred goals for yesterdays game were 1.7 and 2.1, both equating to a 2-0 victory, as i watched the game i thought we should have had about 5, so is this xg a load of bo***x
Click to expand...
It depends on who or what decides on the calibre of chances.
It’s subjective in my opinion and therefore of little more use than all our own views.
 



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