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Phube

Crazy Stat Time!

By Phube, in Leicester City Forum

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KingsX

KingsX

Posted
Posted

All xG is or ever was, is a way to quantify the number and quality of chances (created or given up).  A concept so basic and valuable, fans have discussed it for ages.  The fact that “xG” are now published and discussed as “statistics” shouldn’t cause this much consternation.

 

Sports metrics are abstractions created by businesses using their own unique human eyeballs and algorithms (and creating their own unique results).  They are not necessarily meaningful on a game-by-game basis.  There are always data points that grossly fail the eye test  (to be seized upon by donkey riders as proof that donkeys are better than modern cars.)  But what is useful, is the longer-term mass of data and the trends it reveals.

 

Not all the different xG metrics stem from shots taken.  Fivethirtyeight use both Shot-based and Non-shot xG, the latter an estimate of how many goals a team “should” have scored based on non-shooting actions (passes, interceptions, take-ons and tackles) taken around the opposing team’s goal:

     For example, we know that intercepting the ball at the opposing team’s penalty spot results in a goal about 9 percent of the time, and a completed pass that is received at the center of the six-yard box leads to a goal about 14 percent of the time. We add these individual actions up across an entire match to arrive at a team’s non-shot expected goals.

 

If there was one thing wrong with Cox’s Athletic article, it’s the assumption that everything reverts to the mean (in the long run, goals will roughly equal xG).  No side will vastly under- or over-perform its XG difference in the long run.  But obviously sides who employ the best finishers, will continue to exceed their xG.  No shit, there’s a reason why those guys cost a ton.  Just look at our company atop the more-goals-than-xG table:

 

xGdiff.JPG.e190f4afd21515e88cb42c17b9135962.JPG

 

I happen to think Cox is roughly correct, that we have done well finishing half-chances while creating too few quality ones.  Another needed shot across our bow saying no Vardy, no party.

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Stadt

Stadt

Posted
Posted (edited)
1 hour ago, Ric Flair said:

Has anybody got the xG for us in the 10 games under Rodgers last season vs the goals scored.

 

Also have they got the xG on a game by game basis so I can see the difference when we've farted about with crap formations or not?

132259608_Screenshot2019-10-01at22_10_40.thumb.png.68c2058ac0981dccf17195a3e63d0cf4.png

Website is called understat - great resource as it's the only publicly available xG data as far as I'm aware 

 

 

One thing to note is that there are various xG models available and all of them have differences (whether that be the original data, different weightings for different shots, number of defenders in the way of the shot etc). There's also post shot xG models which are more accurate than the normal model but I don't understand them that well (even as an exponent of expected goals).

Edited by Stadt
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Stadt

Stadt

Posted
Posted
Just now, Ric Flair said:

Thanks, I'm now very interested what the xG is on a game by game basis as I'm convinced that when we play 4-1-4-1 vs when we've played 4-3-3 will be significant. 

I've edited that post, you can click on 'EPL' and the look at xG for and against week by week. Personally, I'm not that keen on taking too much from expected goals models based on one game - its better used to look at longer term trends because there's too much variance in a single game. It's unspoken about how random football is as sport imo, a lucky bounce can decide a game which doesn't happen in other sports. The low scoring nature of football makes it what it is - League 1 Wigan can beat Man City because quality doesn't always prevail which is what makes the sport so magical 

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KingsX

KingsX

Posted
Posted
33 minutes ago, Ric Flair said:

Also have they got the xG on a game by game basis so I can see the difference when we've farted about with crap formations or not?

 

Ric, here are the fivethirtyeight data (defensive xG grayed out).  I think I put the ”crap formations”  matches on the right side.  (Don’t recall how we lined up for Wolves but we did start both Wilf and Hamza).

 

We’re averaging just better than 1.5 xG on the left side, maybe 1 on the right.  A significant difference.  Though I echo @Stadt that xG is limited for analyzing individual matches.

 

morexG.JPG.cd5afd3de2448c9d2c40aae5fb7aae73.JPG

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Facecloth

Facecloth

Posted
Posted
18 hours ago, KingsX said:

All xG is or ever was, is a way to quantify the number and quality of chances (created or given up).  A concept so basic and valuable, fans have discussed it for ages.  The fact that “xG” are now published and discussed as “statistics” shouldn’t cause this much consternation.

 

Sports metrics are abstractions created by businesses using their own unique human eyeballs and algorithms (and creating their own unique results).  They are not necessarily meaningful on a game-by-game basis.  There are always data points that grossly fail the eye test  (to be seized upon by donkey riders as proof that donkeys are better than modern cars.)  But what is useful, is the longer-term mass of data and the trends it reveals.

 

Not all the different xG metrics stem from shots taken.  Fivethirtyeight use both Shot-based and Non-shot xG, the latter an estimate of how many goals a team “should” have scored based on non-shooting actions (passes, interceptions, take-ons and tackles) taken around the opposing team’s goal:

     For example, we know that intercepting the ball at the opposing team’s penalty spot results in a goal about 9 percent of the time, and a completed pass that is received at the center of the six-yard box leads to a goal about 14 percent of the time. We add these individual actions up across an entire match to arrive at a team’s non-shot expected goals.

 

If there was one thing wrong with Cox’s Athletic article, it’s the assumption that everything reverts to the mean (in the long run, goals will roughly equal xG).  No side will vastly under- or over-perform its XG difference in the long run.  But obviously sides who employ the best finishers, will continue to exceed their xG.  No shit, there’s a reason why those guys cost a ton.  Just look at our company atop the more-goals-than-xG table:

 

xGdiff.JPG.e190f4afd21515e88cb42c17b9135962.JPG

 

I happen to think Cox is roughly correct, that we have done well finishing half-chances while creating too few quality ones.  Another needed shot across our bow saying no Vardy, no party.

Read the start of that as Ali G, and was immediately confused lol 

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Yes N'Didi

Yes N'Didi

Posted
Posted
12 minutes ago, Nalis said:

This is the longest run of english champions playing predominantly in blue (6 seasons).

 

The longest run without a team wearing red (as one of their main colours) winning the english championship in 7 seasons.

Thank ****.

 

This is the content I came to see. Absolutely useless and bizarre trivia. None of this sensible debate about xG stats or if anyone knows if Richard Smith owns a skip company.

 

Well done sir.

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StanSP

StanSP

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At 21 years and 314 days, Leicester's Harvey Barnes became the second-youngest player to provide two assists in a Premier League game for the Foxes, behind only Emile Heskey in May 1998 against West Ham.

 

Since Rodgers' first Premier League game in charge of Leicester on 3 March, Jamie Vardy has scored 15 Premier League goals - two more than any other player.

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Aus Fox

Aus Fox

Posted
Posted
26 minutes ago, StanSP said:

At 21 years and 314 days, Leicester's Harvey Barnes became the second-youngest player to provide two assists in a Premier League game for the Foxes, behind only Emile Heskey in May 1998 against West Ham.

 

Since Rodgers' first Premier League game in charge of Leicester on 3 March, Jamie Vardy has scored 15 Premier League goals - two more than any other player.

That’s interesting and all, but what’s the Xg like after yesterday’s game?

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