Do 'Expected' goals statistics suck?

[Filthy Dangles]

I feel like everytime I go under the hood and really look at them, they just do not represent reality.

For example, Moneypuck had this Justin Danforth goal as .16 XG, which to my understanding is them saying this goal should only go in 16/100 times on an average NHL goalie (please correct me if I am wrong). IMO, it's closer to 96/100 than it is 16.




Idk who watched the Rangers/Jackets tonight but it's absolutely laughable that these stats 'say' the Rangers should have won that game most of the time. They were absolutely dreadful defensively and in pretty much all phases of the game.

I feel like I laugh my ass off at the 'Win O Meter' more than half the time they get posted in GDTs/PGT's (again as being wrong and unreflective of reality)

Help me. Am I misinterpreting the information? Should these stats and source (Moneypuck) be thrown out the window? Is there a better source (where you can actually pinpoint specific shots/goals and see their 'expectedness')

 

[SteelCityCannon]

I pretty much hate all the"advanced statistics". They're absolutely meaningless. Way too many variables in hockey.

 

[Mobiandi]

Expected goals has always been a silly stat

 

[Fixed to Ruin]

Yes

 

[Coffee]

Of course it does

 

[ijuka]

I believe expected goals as a predictor for goals are like a 0.36 for correlation.

They're based on historical data, so it means that shots with the same parameters as that one have historically ended up becoming a goal around 16% of the time.

It's a statistical model, they don't actually look at the videos, they just go by the event data.

Also, here the goalie didn't play it correctly at all. If he had moved even a little bit, it wouldn't have looked nearly as free as it was.

 

[Nogatco Rd]

I feel like everytime I go under the hood and really look at them, they just do not represent reality.

For example, Moneypuck had this Justin Danforth goal as .16 XG, which to my understanding is them saying this goal should only go in 16/100 times on an average NHL goalie (please correct me if I am wrong). IMO, it's closer to 96/100 than it is 16.




Idk who watched the Rangers/Jackets tonight but it's absolutely laughable that these stats 'say' the Rangers should have won that game most of the time. They were absolutely dreadful defensively and in pretty much all phases of the game.

I feel like I laugh my ass off at the 'Win O Meter' more than half the time they get posted in GDTs/PGT's (again as being wrong and unreflective of reality)

Help me. Am I misinterpreting the information? Should these stats and source (Moneypuck) be thrown out the window? Is there a better source (where you can actually pinpoint specific shots/goals and see their 'expectedness')

That ‘deserve to win o meter’ is worthless and undermines the many good things that site does put out. I suspect they know this but leave it up since it drives so much traffic to their site (there are always fans looking for reasons their team “should’ve” won)

 

[norrisnick]

To quote one Redmond, Mickey... "expected by whom?"

 

[Chips]

Deserv

I feel like everytime I go under the hood and really look at them, they just do not represent reality.

For example, Moneypuck had this Justin Danforth goal as .16 XG, which to my understanding is them saying this goal should only go in 16/100 times on an average NHL goalie (please correct me if I am wrong). IMO, it's closer to 96/100 than it is 16.




Idk who watched the Rangers/Jackets tonight but it's absolutely laughable that these stats 'say' the Rangers should have won that game most of the time. They were absolutely dreadful defensively and in pretty much all phases of the game.

I feel like I laugh my ass off at the 'Win O Meter' more than half the time they get posted in GDTs/PGT's (again as being wrong and unreflective of reality)

Help me. Am I misinterpreting the information? Should these stats and source (Moneypuck) be thrown out the window? Is there a better source (where you can actually pinpoint specific shots/goals and see their 'expectedness')

Deservee to win o meter is shit, I say as someone who likes advance stats.


You’re better off looking at different individual stats and trying to interpret them yourself.

Expected goals largely correlates with on ice results. Players who get real goals at a way higher or
lower rate than expected tend to level back.

 

[NjDevsRR]

IMO. I think using them in big sample sizes is good. For example, if you look at season to season xGF stats. Majority of the good teams are in the top half , with a few outliers. So it is largely doing a good job identifying good teams.

But using it in single game samples will give you some crazy results many times.

 

[Goptor]

Its one of those situations where you make do with what you've got.

The NHL keeps a lot of data private that public models can't access. The teams also hire anyone talented enough to develop better models and data collection methods and then wipe their work from public access.

You've already hit on one of the major flaws of 'expected goals'. The idea that every goalie has average ability and every skater has an average shot.

 

[Three On Zero]

Most advanced stats are heavily flawed and based too much on subjective opinions by whom is creating them, or interpreting them. Hockey it’s far too reliant on a 5 player system to use stats accurately. They don’t account well for outside sources that can impact them.

 

[StlBigFly]

I feel like everytime I go under the hood and really look at them, they just do not represent reality.

For example, Moneypuck had this Justin Danforth goal as .16 XG, which to my understanding is them saying this goal should only go in 16/100 times on an average NHL goalie (please correct me if I am wrong). IMO, it's closer to 96/100 than it is 16.




Idk who watched the Rangers/Jackets tonight but it's absolutely laughable that these stats 'say' the Rangers should have won that game most of the time. They were absolutely dreadful defensively and in pretty much all phases of the game.

I feel like I laugh my ass off at the 'Win O Meter' more than half the time they get posted in GDTs/PGT's (again as being wrong and unreflective of reality)

Help me. Am I misinterpreting the information? Should these stats and source (Moneypuck) be thrown out the window? Is there a better source (where you can actually pinpoint specific shots/goals and see their 'expectedness')

Imo

Hockey prediction is closer to pinball than baseball. Much closer.

Statistical comparison and probabilistic outcomes are not something many of our brains like but the puck is either on edge or flat when the one timer comes through, the goalie perhaps can’t even see that an opponent is shooting, the puck hits a guy in the pants, then a skate and goes in 5 hole.

This is pure chaos.

Compare this to: guy throws his 52nd fastball and guy swings.

One is way easier to model than the other, much more predicable with results that are way easier to measure even in weird ways.

What advanced stats do and are is just a handful of measuring sticks. They attempt to place the same measuring stick on every team, player, and event. They can’t help their job is to define chaos.

The root of your problem is ice hockeys chaotic nature, not the evaluation of it.

Understanding their fundamental source will allow you to recognize them for what they are.

I’d suggest that they’re a great tool that joins others to help describe historic events and predict future ones.

 

[Freudian]

Before xG people had to watch the game to claim their team that lost deserved to win. Now they don't have to do that. Progress.

 

[JaegerDice]

xG models are good and useful PREDICTORS over large samples.

That is why the best xG teams tend to perform best over the course of a season or playoff run.

The deserve-to-win ometer is for one game, and using predictive measures to describe how a game went isnt particularly useful.

 

[Bounces R Way]

They are total junk in their current form. A 4th line plug shoveling three successive short range shots directly into a goalie who has the post sealed off at the side of the net is worth something like 10x the xGs of an open Ovechkin cross ice one timer. There's too much noise in a flow game like hockey to have the gall to claim to know how many goals you can expect to score from math.

That isn't to say they're not worth recording or considering, or that the concept isn't worth refining, but they need to be taken as part of a picture. And that part should be around 20% or so IMO.