Let’s talk about NBA stats

[HermanG]

What do you mean by ignoring volume? It simply replaces the actual result of a possession with the expected value of that possession.

Can’t say for certain what luck adjustment formula Krishna used. But you can google a lot of the popular methods. Nathan Walker is the first guy who started doing luck adjusted stuff. He works for a team now though, so his stuff might have been taken down from the web. Here’s an article explaining LA methods in long form:

Nylon Calculus: Defining and calculating luck-adjusted ratings for the NBA

On-off data is the most basic data available for tracking how a team performs when a player is on or off, but it can be improved with luck-adjusted ratings.

fansided.com

Just a question. I'm not well acquainted with most of the all around stats and asking silly questions to get grasp of what the number is about.

 

[HermanG]

Quality of the look is often considered in this LA adjustment methods. Like I said before, I can’t speak to what Krishna did specifically. The expected value has to be created somehow.

But regardless, the reason why LA became in a thing in the first place is because the things they adjust for, there is a statistical argument to show that it is actually random. I guess each person is free to determine if it’s actually random based on feel….but a lot of work has been done to investigate what is or isn’t random.

The thing about functioning better as team…that affects both the raw and the luck adjusted. Like if you put 5 non-shooting C’s on the court. Their plus minus would be cooked and not be representative of their true ability. Doesn’t matter if it’s raw or luck adjusted. I suppose lineup compatibility could be a potential explanation as to why certain times are lucky are unlucky….but there is also potential for a team to be lucky with bad lineup compatibility and unlucky with good lineup compatibility. There is some degree of randomness in every situation.

I thought one of the biggest critique towards APM was based on the fact that things like coaching and roster compatability arent really accounted for. Maybe the LA-RAPM actually sort of "tries" to address this as it doesnt punish player for the bad fits (which of course could be caused by the player in some instances). But if you balance out the impact of incompatability, you also stop rewarding compatability.

I think OG who is very impactful off the ball falling from 1 to 282 and Chet who is crucial to OKC lineup ifts falling from 18 to 307 sort of support that the LA-version can overcorrect pretty massively.

 

[HermanG]

For what its worth though, it seems to correct guys mostly towards the correct direction (personally biased opinion here).

 

[KqWIN]

I thought one of the biggest critique towards APM was based on the fact that things like coaching and roster compatability arent really accounted for. Maybe the LA-RAPM actually sort of "tries" to address this as it doesnt punish player for the bad fits (which of course could be caused by the player in some instances). But if you balance out the impact of incompatability, you also stop rewarding compatability.

I think OG who is very impactful off the ball falling from 1 to 282 and Chet who is crucial to OKC lineup ifts falling from 18 to 307 sort of support that the LA-version can overcorrect pretty massively.

It is still a chief criticism, but that's not necessarily what LA tries to address. There is some degree of randomness in the make or miss game and that's what LA tries to address and you've got to start there. Having said that, I would agree that LA tends to overcorrect and there are valid reasons to think that there is more than "luck" that caused the actual values. For example, lets just say reality shows that Sexton's teammates shot 30% when LA (using whatever method) expected them to shoot 40%. I'm definitely open to the idea that LA overcorrects because the lineups Sexton plays in have bad synergy. But you also have to accept that no matter what the lineup, randomness is still present. A player can be in perfect lineups 100% of the time, but there's still a possibility his teammates miss more shots than they should due to chance.

I think you could argue LA does do a better job of addressing compatibility than raw, but it would be an indirect consequence that follows from the primary goal. This is why I said earlier that it's totally reasonable to have different feelings on LA and it's usefulness. I wouldn't hassle with anyone who felt strongly that one is better than the other, but personally I think it's good to consider both.