Contested vs. Free Rebounds in the Bucks-Bulls game

I’m really obsessed with the distinction between “contested” and “free” rebounds.  I’m curious to know how many rebounds in any given game can be classified as “gimmes” and which players tend to get the most “gimmes”. 

So on Saturday during the second half of the Bucks-Bulls game I recorded, as best I could, the number of “contested” versus the number of “free” rebounds.  I actually split the categories into 4: “contested” offensive boards, “contested” defensive boards, “free” offensive boards, and “free” defensive boards. 

BUCKS vs. BULLS (types of rebounds gathered)

  C Off C Def F Off F Def
Bogut 3 4 0 1
Moute 1 0 0 0
Maggette 0 2 0 0
Salmons 1 0 0 1
Delfino 0 1 0 0
Boykins 1 0 0 0
TOT 6 7 0 2
Noah 0 0 0 2
Watson 0 0 0 2
Brewer 1 1 0 1
Deng 0 0 0 1
Bogans 0 0 0 1
Rose 1 2 0 0
Boozer 0 1 1 2
Asik 3 0 0 2
Korver 1 0 0 0
TOT 6 4 1 11

A note of caution.  The above numbers are not “According to Hoyle” accurate.  For instance, on several occasions I took phone calls and my attention was not sharp, and on other occasions I had a hard time identifying some of the Bulls players (I think I ended up generically giving the rebound to “Watson”).  But more importantly, in retrospect I am not happy with my definition of “free” rebounds.  (EDIT: Although my numbers are not neccessarily accurate to the player, I just checked the box score on basketball-reference and the numbers comport exactly with the offensive rebounding percentages from the game.) 

My definition of “Free” Rebounds

I counted as “free” rebounds any rebound grabbed with no opposition within arms reach.  By that definition, about 35% of the rebounds grabbed in the game where “free”.  Most of the free rebounds were grabbed by the Bulls players on their defensive glass. 

However, about halfway through the second half I started to dislike my definition of “free” versus “contested”.  I was defining the exact same type rebound differently based upon circumstances outside the rebounders control.  Let me explain.

In the second half of the game, the Bucks rarely contested their offensive boards.  On the other hand, the Bulls always had at least one player in offensive rebounding position.  As a result, on several occasions I was counting defensive rebounds for the Bulls that required a certain amount of energy expenditure (meaning, the player had to hustle in some manner to get the basketball) as “free” simply because no Buck chose to be in a rebounding position on that possession.  On the other end the same type rebound was being classified as “contested” simply because Omar Asik or some other Bull was nearly always standing in the lane.  I don’t know if that is a fair statistical distinction.  How would the Bulls players who grabbed the so-called “free” rebounds know that no Buck was in the vicinity at the time of the act?   They couldn’t.

Had I changed the definition of “free” to what I really meant to chart — “effortless” rebounds — (in other words rebounds that came directly to a player or rebounds that did not require the player to move or exert energy other than an unnecessary jump), then the number of so-called “free” rebounds would have been reduced drastically.  Next Bucks game I am going to record rebounds in that manner.  (Its better than watching the game).

Probably less of a problem than I imagined

I’ve been worried that Marginal Win Score numbers might be skewed by “effortless” rebounds falling to certain players in an uneven manner.  I think now that I was worrying about nothing.

Andrew Bogut, for instance, grabs an inordinate amount of the Milwaukee Bucks rebounds.  But he works much harder than any of his teammates to get those rebounds.  Why shouldn’t he be rewarded for his effort?  Same deal with Kevin Love.

Yes, there are occasions where a more assertive rebounder will grab a larger share of uncontested rebounds, but don’t you want assertive rebounders?  Aren’t they a good thing? 

Besides, after concentrating on the matter, I’m not even sure its worth distinguishing between “free” and “contested” rebounds.  Generally speaking, the same amount of effort goes into a given rebound whether an opposition player is in the area or not. Completely “effortless” rebounds are rare, and so are rebounds where two opponents fight over the ball.  The vast majority of rebounds require a certain degree of hustle and exertion, along with fortuitous bounces and superior positioning.

As a footnote, I’ve always thought it would be interesting to see what would happen if more teams ordered their frontline players, even their small forwards, to challenge for every offensive rebound.  Would they suffer more fastbreak points given up?  There’s evidence that is possible.  But, I think overall the result would be positive, especially for poor shooting teams like the Milwaukee Bucks.  I don’t know why the strategy has never been employed.

4 Responses to “Contested vs. Free Rebounds in the Bucks-Bulls game”

  1. Chicago Tim Says:

    I don’t know if that strategy has been employed as such, but there are certainly teams that emphasize offensive (as well as defensive) rebounding, and the Bulls are one of them. That was true even while Noah was out injured — maybe even more true, since they could not rely on Noah. Noah can have an incredible number of offensive rebounds, but Boozer, Gibson, Thomas and Asik also collect a good share.

    Deng is the small forward, and sometimes he focuses on rebounding. Other times, though, he focuses more on scoring and/or defending the perimeter, so his offensive rebounding isn’t quite at the level of the others.

    The Bulls are really a poor shooting team, especially compared to the other contenders. They need more possessions to win the game.

    I would note that many offensive rebounds seem to come off of Rose drives to the basket. It almost seems like they should be counted as assists, which would certainly improve Rose’s assist rate and his shooting percentage. But it’s true, one reason Rose can get away with driving and missing is that he often draws so much attention that one of the bigs can tip it in.

  2. tywill33 Says:

    When I played, in any variation, I was a perimeter player, and I rarely crashed the offensive boards. I think my thinking was threefold. One, its probably a futile effort. Two, it involves a lot of extra energy, because if you don’t get the rebound you have to scramble the other way. Three, offensive rebounds are tacitly considered “bonus” rebounds.

    I think the last reason really dictates the tendency not to go kamikaze on the offensive glass. I’d like to see it tried somewhere though, just to see what the effect would be.

    As for the Bulls, Asik was grabbing a nice share of the offensive rebounds. It seemed that he decided, wisely, that if he had no role in the offense he might as well concentrate his efforts on the offensive glass. I wish other non-perimeter threats would take up that notion.

  3. Ravenred Says:

    Did you keep any tabs on boxouts?

    One of the early comments on Bogut was that he boxed out quite a bit for the other players on the team (ahh… the days of ol’ Stonehands Magloire and I-almost-wish-we-had-him-now Joe Smith).

    Be interesting to correlate “free” rebounds achieved on court with particular players who DIDN’T get the board (a +/- for rebounding, pretty much).

  4. James Says:


    An alternative approach might be to look at rebounds that a player grabbed on his own vs. rebounds that other players on the same team could have just as easily had. It seems to me that the primary argument used by opponents of WoW is that players are taking rebounds from their teammates; that is, rebounding is overvalued in WoW because any given teammate could have grabbed a number of rebounds that one player had. I.e., sure Kevin Love got 20 rebounds, but 10 of those could have gone to Beasley if Beasley didn’t let love have the easy ones. Anyway, I just thought that might be interesting to consider.

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