Effective Rebounding Rates

Earlier in the season I wrote myself the following note while watching a Clippers game:

Is Baron Davis really a “very good” rebounder for a guard? How would we determine this?

(Please continue once you’re done laughing at the fact I was actually watching a Clippers game.)

This note was the result of listening to one of the announcers proclaim that Baron Davis is a “very good” rebounder for a guard. Naturally, I would like to know how we might classify people as “very good” rebounders.

More recently, I’ve heard announcers praise Jason Kidd for being the best rebounding point guard in the NBA. This comment naturally comes from his high rebounding totals, but what do his rebounding rates look like?

Using Rebounding Rates Instead of Rebounding Totals

We all know that rebounding rates, not rebounding totals, give us the best picture with respect to offensive and defensive rebounding. That said, I think we can paint a better picture using more than raw rebounding rates.

Thus the question I asked myself was: “What if we look at rebounding rates based on the shot location?”

My hope is that by using shot location data we can get a sense of how rebounding rates for different positions change based on the shot location. Also, we can use this data to neutralize a player’s rebounding rate based on these shot locations, since players do not face the same shot distributions while on the court.

Shot Locations

Using data from the ’07-’08 season, I collected the number of rebounds each player obtained and missed while on offense and defense based on rebound opportunities coming from the following shot locations:

• Low Paint – The area in the paint within 6 feet of the hoop
• Mid-Range – All other 2pt shots
• 3pt Shots
• Free Throws

With these rates in hand, I neutralized each player’s offensive and defensive rebounding rates to create an effective rebounding rate metric that weights rebounding rates based on the average distribution of rebounding opportunities from the ’07-’08 season.

This means that a player’s effective rebounding rate is calculated by weighting the player’s low paint rebounding rate by 25.8%, the mid-range rebounding rate by 43.3%, the 3pt rebounding rate by 24%, and the free throw rebounding rate by 6.8%.

The Results

The spreadsheets below list the results of performing the calculations listed above. The results are grouped by position, with the players sorted from highest effective rebounding rate to lowest effective rebounding rate.

It is worth noting that players that did not have at least 100 opportunities from each shot location on offense and defense were removed from this data set.

The following spreadsheet lists the offensive rebounding results:

http://spreadsheets.google.com/ccc?key=pLJimPjd7oquI6XwF2O5IUQ

The following spreadsheet lists the defensive rebounding results:

http://spreadsheets.google.com/ccc?key=pLJimPjd7oqthtSWrpCsFOw

Back to Baron Davis and Jason Kidd

On offense, Baron’s effective rebounding rate ranks him as the #6 offensive rebounding point guard of ’07-’08, while Jason’s effective rebounding rate ranks him as the #4 offensive rebounding point guard of ’07-’08.

On defense, it’s safe to say Kidd was a monster in ’07-’08. His effective rebounding rate ranks him as the #1 defensive rebounding point guard of ’07-’08, while Baron’s effective rebounding rate ranks him as the #10 defensive rebounding point guard of ’07-’08.

In ’07-’08 at least, it’s safe to say these guys were very good rebounders. I was surprised to see just how high Jason Kidd’s defensive rebounding rates were. Also, his ability to obtain that percentage of rebounds on free throws is impressive. Makes me want to watch some tape and see what he’s doing differently than other point guards.

What this doesn’t tell us

Unfortunately this doesn’t give us much insight into what external forces affect the player’s rebounding rates. This measure does not capture important components like teammates, opponents, and coaching philosophies. That said, I believe this is worth looking at to hopefully provide a source of motivation for tackling these issues in the future.

Future Work

One idea I have for the future is to try and relate rebounding rates to shot distance. In the end it might make more sense to use discrete shot locations, but I’m interested in seeing if there are any general curves that form based on the distance of the shot from the basket.

As mentioned in the previous section, work can be done to try and determine how teammates, opponents, and coaching philosophies relate to a player’s individual rebounding rates. Lastly, I’m hoping to see how aging curves fit to these rebounding rates. I’ve got a lot of historical play-by-play to parse before I can do that, though.