Other guys get lower rebound numbers than their true skill level might predict, because the play with teammates who are adept at tracking down the ball. I'm thinking particularly of Rick Adelman's Portland teams, when Buck Williams, Jerome Kersey, and Clyde Drexler were all excellent rebounders at their respective positions.

1. New coach different scheme on both sides of the court.
2. projected starters only played 6 games together
When lebron left Cleveland so did his role. you would be more apt to compare the 2011 miami team to the 2010 Cleveland team since he pretty much filled the same role.

bottom line is there are too many variables and overall changes to use lebron example to refute Neil's conclusions

I think this study just shows that the baseline skill level within a position varies depending on the statistical category. It suggests that we should be wary of overvaluing the ability to put up big assist or rebound percentages, because the typical player at that position would be able to approximate those percentages if put in the same situation.

However, something like usage, turnover avoidance, or the two boxscore defensive metrics (steals & blocks) are harder to replace -- it's not a given that the typical player at a position would be able to duplicate those rates if put in the same situation.

I'm posing the critical question: isn't role a function of player skill?

This seems to confirm Phil Birnbaum's research that much of rebound rate (particularly defensive rebound%) is more a product of team roles and positional designations than actual skill.

Neil, I don't have your data, so I say this somewhat tentatively, but I don't find the conclusion you are reaching from the data to be the only or necessary one, and for that reason, I'm not sure I am convinced yet.

Take rebounding or assists, for example. Couldn't this data indicate that coaches/GMs are relatively good at assigning (or in this case replacing) roles based on player skill? If a team loses Deron Williams, for example, they don't replace him with Paul Milsap. Instead, Willams is replaced by Devin Harris, and although Devin is not identical to Deron, their skills -- and thus the role assigned to them -- are similar.

http://www.basketball-reference.com/play-index/pcm_finder.cgi?request=1&sum=0&p1=willide01&y1=2011&p2=harride01&y2=2011

As a Pistons fan, I can think of another example - Stuckey and Bynum. If Stuckey doesn't return to Detroit, he could be replaced in the starting lineup by Bynum. Given their historical production, you'd see a very high correlation for USG rate, AST%, BLK%, etc. To say that this has more to do with their role than skills, however, seems very strange to anyone who has watched the players play, specifically because their skill sets are very similar. And as a direct results of those skill sets, they play (mostly) the same position.

http://www.basketball-reference.com/play-index/pcm_finder.cgi?request=1&sum=0&p1=stuckro01&y1=2011&p2=bynumwi01&y2=2011

Obviously, I'm sort of cherry picking a pretty easy example here (and I can think of plenty more off the top of my head), but I'm curious how often this would be true of the player seasons you've identified.