How should we think of +/- stats in different eras?

[ceiling raiser]

Something to pine about a bit…

In an era with more *team level* parity, particularly like the 70s NBA, how likely is it that *player level* data would be subject to tighter distributions?

Don’t have a ton of data, but consider the example of a KAJ. If he’s a +6.0 player in the 70s, what does that mean in an era from the mid 00s-mid 10s where you have 2-3 60 win teams a season?

RAPM I assume would not be subject to this issue given it’s regressed with a much higher n possessions. But I almost wonder if the Pollack +/- data for Erving is somewhat deceptive.

A worthwhile study might be mapping +/- data vs z score of SRS vs RAPM in the databall era.

[OhayoKD]

not sure how it affects later periods, but as has been covered, it makes a big difference in the 60's

[Doctor MJ]

Something to pine about a bit…

In an era with more *team level* parity, particularly like the 70s NBA, how likely is it that *player level* data would be subject to tighter distributions?

Don’t have a ton of data, but consider the example of a KAJ. If he’s a +6.0 player in the 70s, what does that mean in an era from the mid 00s-mid 10s where you have 2-3 60 win teams a season?

RAPM I assume would not be subject to this issue given it’s regressed with a much higher n possessions. But I almost wonder if the Pollack +/- data for Erving is somewhat deceptive.

A worthwhile study might be mapping +/- data vs z score of SRS vs RAPM in the databall era.

So first, check out the analysis I just added to your other thread. It's noteworthy, I think, that the Russell-era Celtics seem like the most dominant superstar-defined run still, and perhaps reduces the urgency of considered era differences.

With that said, I do think that PM per Minute lists would put older guys at a disadvantage because a guy like Russell was certainly pacing himself over the course of his game in a way that modern players aren't necessarily.

(Tangent: Something Ben Taylor is fixated on when it comes to soccer is how drastically the game would change if you just let there be substitutions like you can have in other major field sports - basketball, hockey, American football. Guys spend a lot of time just standing around out there, and that would probably die if you just let guys rest and then come back in...which would then probably make it a lot less likely to have World Cups decided by penalty kicks.)

Back on topic:

I think the big thing we're really asking here is how impactful players were back before there was good data to figure out what was working.

My feeling in general is that if we had the data, we'd see a lot more HOFers like Erving whose +/- data showed they didn't really have impact in many years to match what we'd expect given their stature, and what that stature would mean today.

But then you'd also have other guys, perhaps even guys that are hard to detect with just box score stats, whose style of play was inherently additive to their teams. Among the superstars Russell and Jerry West seem likely to fit this mold, but what about the lesser players?

Re: Erving +/- data deceptive. Curious to hear you specifically elaborate on this. If what you mean is:

1) Not so unusual for his era.
2) Still quite valuable because of the tactical attention he drew - maybe opponents should have been focused on Bobby Jones more and Julius Erving less, but the attention Erving drew when opponents schemed against Erving's team did have value.
3) Potentially more resilient and thus more impactful in the playoffs.

Then I get it.

I have to say though it will still hurt him in my book compared to the level of guys I tend to compare him to.