APBRmetrics

I suspect that the reason that studies haven't found much influence of teammates is that most lineups are going to be at least within shouting distance of being solid and reasonable.

That is, pretty much every minute of an NBA game you're going to see your team have on the court one player with very good ball-handling skills, maybe two, rarely 3. You're going to see maybe one real big guy, maybe none (some teams have to make do with playing a PF out of position), almost never two. In terms of big-but-not-real-big guys, you'll usually see two, maybe one, almost never three (those recent Piston teams being an exception).

Similarly with a mixture of outside shooting skills and inside skills, and to a certain extent defensive ability (putting more than one or two bad defenders out there really starts hurting your team; e.g. regardless of how good Jeremy Lin could've potentially been on offense, the Rockets couldn't afford to start both him and Harden, they were just getting roasted on defense. Beverley was a much better backcourt mate for Harden.) Teams will generally put standard conventional lineups on the court.

It's like trying to separate the contributions of Karl Malone vs John Stockton; hard to do if they're always playing on the court together. If the players that we observe in the NBA are spending most of their minutes with reasonably complementary players, we won't see much impact of different teammates.

But if we had a number of teams doing, not just the Detroit experiment, but doing weird stuff like playing four centers at once, or three point guards and two big guards, I think we'd see more dramatic effects of changing teammates. We just don't observe situations like that very often. E.g. adding Bill Russell to the Celtics caused a big improvement. If they'd added Kareem Abdul Jabbar instead, they would've also improved greatly (probably not quite as much but still a big improvement). But if they'd added Russell, and then added Jabbar on top of that, Jabbar's impact could not have been as large (unless the Celtics did something like play each of them only 24 minutes per game, so that they never interfered with each other).

So instead we see Jabbar's impact on the Bucks and the Lakers, and no matter where he played, he had a big impact. We don't see the weird situations where his impact might've been different, such as getting added to the 1960s Celtics.


It might be interesting to look at the situations where teams have done weird things with lineups: Detroit with their 3-big-men frontline; twin towers such as Wilt+Thurmond, maybe Olajuwon+Sampson and Bellamy+Reed too. Small ball lineups which seem to becoming a little more common in recent years. Lineups with nothing but offensive black holes, i.e. nothing but gunners and non-passers. Do we see players having different values in those situations? The problem is that I suspect that the number of minutes is too small to make decent estimates.

Nate wrote:I think a fundamental issue here is that you can't answer all questions well with a single statistical measure.

So far, most if not all the research I've done points at the fact that players don't have much influence on each other's impact. I find that hard to believe, myself, so there's more work to be done.

I'm assuming that you mean "the difference in the team effects of various NBA players seems to be small". Playing 4-on-5 is probably not going to go so well for the 4-man team.

Common sense would tell us to look at the player's skill set & positions. Chris Paul and Ty Lawson probably isn't the greatest fit, but CP3 can definitely work with almost any non-high-usage player

Yeah, it's pretty clear that position relative to the ball and position relative to the hoop are big factors in how much impact a player can have on the game - especially as measured by box scores. If nothing else, inside players rebound more, and players have to have the ball to shoot. Ostensibly something like SportsVU would help control for opportunity. A more subtle aspect is separating the impact of the players' role from the impact of the players' ability.