As well as VAR another newer thing in football is the xG (expected goals) statistic, and unsurprisingly Man City fans are whinging that this too is evidence that Liverpool are undeserving of their success.
In a complete misunderstanding of probability they have claimed Liverpool don't deserve to be winning the league since Man City are top of the xG league.
xG tells you the averaged probability of scoring a goal in different situations, like a header inside the 6 yard box or a volley from 30 yards.
The xG for a penalty is 0.76. This means on average a penalty is scored 76% of the time. xG is averaged over many players in many teams in many leagues over many years.
xG is calculated based on professional players but doesn't take the specific player into account.
James Milner has scored 17 penalties in the Premier League and missed 2. So he has a penalty conversion rate of 89%.
Is Milner luckier than the average penalty taker? Or is he just better?
If you're deluded and think he's lucky you would take Milner off penalties because you'd expect him to miss the next 4 penalties so he returns to the average of 76% conversion.
If you think he's better then you tell him to keep taking penalties because he's probably going to score the next 4 penalties.
Elite sportspeople do not revert to the mean. Things evening out over a long enough time is in the context of random events or 50/50 decisions. The point of having skill is to outperform random results. And the point of being [HASHTAG]#worldclass[/HASHTAG] is to outperform other top professionals.
So it shouldn't be surprising that the best team in the best league is frequently doing better than xG suggests.
xG also has nothing to do with "fair". It isn't fair for a game to end in a draw just because both teams have the same xG. If teams have the same xG, the one with better players most likely wins. This is like the idea of saying "we'll make it an end to end game and back our players to score more than yours".
Teams don't "deserve" to score 76% of penalties and you aren't unlucky if you miss 50%, you're just crap at them.
xG isn't perfect, it's just information. It's better than shots on target which was previously used as the main way to measure scoring chances.
You can win a game with zero shots on target by putting a cross into the 6 yard box and a defender scores an own goal trying to stop a tap in. That doesn't mean shots on target are meaningless at how you do in a game, just that they don't tell the whole story.
xG doesn't tall the whole story either but at least it takes the quality of the chance into account, not just counting all hoofs towards the goal as equally valuable.
A large xG is a good sign that you're making lots of chances, but also that you're wasteful if the actual goals scored isn't also high.
Some recent results:
Spurs 0-1 Liverpool (1.10-1.78)
Liverpool 2-0 Man Utd (2.01-1.42)
Wolves 1-2 Liverpool (1.84-1.26)
But we deserved to beat Wolves even though they "won the xG". Alisson deserved to make his save against Jiménez because his positioning was perfect, not average. Firmino deserved to score the winner because his finishing was perfect, not average.
If we had average players we would have scored about 6 fewer goals this season and conceded about 7 more goals. It's not actually that simple though, because different players would play in different ways and not make the same chances in the first place.
xG is like imaging what would happen if just as an opponent was about to take a shot you teleport out Alisson and replace him with someone like Pickford. Of course we would concede more goals and be lower in the table.
Man City have scored more goals than us but their actual goals and xG is almost identical. That just means they make lots of chances (De Bruyne) but their strikers aren't doing anything special. Sterling loves a tap in but how many screamers can you remember him scoring?
In a complete misunderstanding of probability they have claimed Liverpool don't deserve to be winning the league since Man City are top of the xG league.
xG tells you the averaged probability of scoring a goal in different situations, like a header inside the 6 yard box or a volley from 30 yards.
The xG for a penalty is 0.76. This means on average a penalty is scored 76% of the time. xG is averaged over many players in many teams in many leagues over many years.
xG is calculated based on professional players but doesn't take the specific player into account.
James Milner has scored 17 penalties in the Premier League and missed 2. So he has a penalty conversion rate of 89%.
Is Milner luckier than the average penalty taker? Or is he just better?
If you're deluded and think he's lucky you would take Milner off penalties because you'd expect him to miss the next 4 penalties so he returns to the average of 76% conversion.
If you think he's better then you tell him to keep taking penalties because he's probably going to score the next 4 penalties.
Elite sportspeople do not revert to the mean. Things evening out over a long enough time is in the context of random events or 50/50 decisions. The point of having skill is to outperform random results. And the point of being [HASHTAG]#worldclass[/HASHTAG] is to outperform other top professionals.
So it shouldn't be surprising that the best team in the best league is frequently doing better than xG suggests.
xG also has nothing to do with "fair". It isn't fair for a game to end in a draw just because both teams have the same xG. If teams have the same xG, the one with better players most likely wins. This is like the idea of saying "we'll make it an end to end game and back our players to score more than yours".
Teams don't "deserve" to score 76% of penalties and you aren't unlucky if you miss 50%, you're just crap at them.
xG isn't perfect, it's just information. It's better than shots on target which was previously used as the main way to measure scoring chances.
You can win a game with zero shots on target by putting a cross into the 6 yard box and a defender scores an own goal trying to stop a tap in. That doesn't mean shots on target are meaningless at how you do in a game, just that they don't tell the whole story.
xG doesn't tall the whole story either but at least it takes the quality of the chance into account, not just counting all hoofs towards the goal as equally valuable.
A large xG is a good sign that you're making lots of chances, but also that you're wasteful if the actual goals scored isn't also high.
Some recent results:
Spurs 0-1 Liverpool (1.10-1.78)
Liverpool 2-0 Man Utd (2.01-1.42)
Wolves 1-2 Liverpool (1.84-1.26)
But we deserved to beat Wolves even though they "won the xG". Alisson deserved to make his save against Jiménez because his positioning was perfect, not average. Firmino deserved to score the winner because his finishing was perfect, not average.
If we had average players we would have scored about 6 fewer goals this season and conceded about 7 more goals. It's not actually that simple though, because different players would play in different ways and not make the same chances in the first place.
xG is like imaging what would happen if just as an opponent was about to take a shot you teleport out Alisson and replace him with someone like Pickford. Of course we would concede more goals and be lower in the table.
Man City have scored more goals than us but their actual goals and xG is almost identical. That just means they make lots of chances (De Bruyne) but their strikers aren't doing anything special. Sterling loves a tap in but how many screamers can you remember him scoring?
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