New Rebounding Statistic

[Kirobaito]

I've been thinking about this for about five years now (since I took AP Statistics my senior year of high school).

There needs to be a new rebounding statistic measured, which I'm tentatively calling REB+ (to mimic the OPS+ statistic in baseball). Regular rebounding rates are flawed, because they are too swayed by field-goal percentage and opponents' field-goal percentage. A defensive player should get the rebound, based on positioning on the court. So, a team that shoots significantly better than their opponent should come away with more rebounds, with rebounding ability being equal. Last year, the Boston Celtics shot over three percentage points higher than their opponents (48.3-45.1), but came in behind in total rebounds. How bad were they at rebounding? Even worse than the regular statistic. A team being outrebounded doesn't necessarily make them a bad rebounding team. Maybe it's their huge field goal percentage disparity with respect to their opponents.

Some of the things we'd need to do:

1) Separate field goal misses from free-throw misses on 2nd shots/and-ones. We want to consider them separately, because 95% (guess) of the time the defense gets the rebound on a missed free throw, compared to around 70% of the time on field goals.

2) Calculate offensive rebounding percentage, defensive rebounding percentage, FT oreb percentage, and FT dreb percentage for every team.

3) Get the total percentages for the entire NBA, so we can set up a normalized system of measurement (with 100 being average, like OPS+ in baseball).

4) The last part is that some statistician needs to find an appropriate way to weigh all of these four rebounding percentages relative to one another. Maybe weigh them based on total number of rebounds for each one? So, field goal defensive rebound, field goal offensive rebound, free throw defensive rebound, free throw offensive rebound.

Our end result should be a single number that best encapsulates a basketball team's ability to rebound the ball, with 100 being average. There are probably other factors to consider that I'm forgetting, but at the very least it would do better than the current system of just using total rebounds, which is incredibly flawed.

Any thoughts? Criticisms? Does something like this already exist that I haven't noticed?