Shabazz's Rebounding

Shabazz Muhammad's season ended on Friday at the hands of Minnesota. The Bruins had two big things working against them: the injury to Jordan Adams and the task of keeping Minnesota off the boards. The Golden Gophers are first in the country in offensive rebound percentage, grabbing 44% of their missed shots. On the other hand, UCLA has struggled all season long with rebounding. They rank 206th in the country in offensive rebounding and 264th in the country in defensive rebounding. At 6'6", Shabazz's personal OReb% was a solid 9.9%, but his DReb% was an awful 8.5%. To put that into perspective, Gonzaga's 5'11" David Stockton's was higher this season (9.2%).

Trying to keep Minnesota off the offensive glass had to have been a main priority for Ben Howland on Friday. The Bruins as a whole actually did a pretty good job of this. Minnesota had 10 offensive rebounds (32.4% OReb%, well below their season average). Still, if you look at the box score you will see that Shabazz had ZERO defensive rebounds in 39 minutes. That's actually pretty hard to do, you would think a ball is going to fall in your lap at some point in the game. 

How does an athletic 6'6" forward not get a single defensive rebound in 39 minutes? Well to answer that question I decided to go back and look at the film. Of Minnesota's 10 offensive rebounds, Shabazz was on the court for nine of them. The photos below highlight where Shabazz was on the court when Minnesota got their nine rebounds.

1. In good position but flat footed, spectating

For Shabazz's sake, I was hoping the reason for his lack of rebounding was to leak out in transition. Although this might not be an optimal strategy, it would mean there is at least an advantage to his lack of rebounding. Otherwise, Shabazz is simply very bad at the skills involved in rebounding or not hustling (or both). This first attempt shows a flat footed Shabazz under the hoop. In his defense, he has three UCLA teammates in the paint with him.

2. Boxing out

The problem with this analysis is we can't be sure of Howland's gameplan. Basketball purists are quick to teach the box out, but the fact is that's much easier said than done against Minnesota. Still, I think it's safe to say that Shabazz did a pretty good job on this possession

3. Late getting back in transition

Here Minnesota got an easy put back in transition off of Shabazz's miss on the other end. He was very late getting back, but we're not too concerned about this one in terms of rebounding ability.

4. Sort of boxing out the shooter

Shabazz was guarding the initial shooter on this one. He didn't box out immediately, but at least tried to recover after he realized the ball wasn't going in.

5. Flat footed, spectating

The ball doesn't go to Shabazz's side, but he is still pretty much just standing and watching the play unfold. This is an example of the worst scenario for Shabazz. There are obviously very few times in a basketball game where standing and watching isn't a bad thing.

6. Elevating for the rebound 

Shabazz gets his hand on this ball, but was not able to come up with it. The ball got batted out for a long rebound. By getting his hand on the ball, he may have prevented  an easy layup for Minnesota (even though they were still able to maintain possession).

7. Flat footed, spectating

Another negative play for Shabazz. He's not boxing out or going after the ball. He's not even leaking out, he's just standing and watching.

8. In good position but flat footed, spectating

More of the same here.

9. A bit more of pursuit

Shabazz took steps towards the basket to potentially grab a rebound, but the ball bounced off the rim hard. You can see in the photo he is changing his momentum to either try to continue to pursue the ball or possibly to leak out.

Obviously, this analysis is only nine plays from one game and is by no means definitive. I'll let the film speak for itself and not over generalize, but Shabazz's rebounding (and motor) might be a long term concern for his NBA career. Statistically, his rebounding numbers are somewhat similar to DeMar DeRozan. DeRozan was a pretty good offensive rebounder and a not so good defensive rebounder, but not quite as bad as Shabazz.

Minnesota and Rebounds: The Art of Cherry Picking

Last month, I looked at Bucknell and turnovers in college basketball strategy. Another interesting team in the 2013 season has been Tubby Smith's Minnesota team. The Golden Gophers rolled through non conference play, but are just 8-9 in the Big Ten. Despite the struggles, Minnesota is still 16th in efficiency in the country largely due to a ridiculous offensive rebounding percentage.

Minnesota ranks first in the OReb% by a wide margin and just 239th in DReb%. Offensive and defensive rebounding aren't exactly the same skill by any means, but it doesn't make sense that a team would be so far off in the two categories. Instead, I think that the large difference is more a product of the coach's system. Here are the two schematic possibilities for Minneosta's differential.

1. Cherry picking - Minnesota is great at rebounding, but they decide to cherry pick (get out in transition) instead of having everyone defensive rebound.
2. Allowing cherry picking - Minnesota is not quite as good at rebounding as their OReb% indicates, but they decide to crash the glass relentlessly on offense instead of worrying about transition defense.

The point here is that there is a natural trade-off between rebounding and transition plays.

To further examine this, I first looked at teams with the biggest differentials between offensive and defensive rebounding. To do this, I took the z-score of each, meaning I found how far away a team's OReb% and DReb% are away from the NCAA averages.

The 10 teams on the left are all Minnesota-like. They are much better at offensive rebounding than defensive rebounding. This means we would expect a much higher number of transition players per game than the teams on the right. The teams on the right are conservative when it comes to rebounding (notice Bucknell again). They get back on defense instead of going for offensive rebounds and box out instead of cherry picking. In both cases, the two strategies by the teams on the right limit plays in transition.

I decided to put this theory to the test using hoop-math.com. Using the data from that site, we can see how often these teams both go in transition on offense and allow transition plays on defense. I did this by looking at the percentage of times a team shoots in 10 seconds off missed shots versus the percentage of times a team shoots in 11-35 seconds into the shot clock off missed shots.

The table above illustrates the trade-off between cherry picking and transition. The teams on the left (the cherry pickers) are in transition 42% of the time and allow transition 41% of the time. The teams on the right (the conservatives) are only in transition 32% of the time and allow transition only 35% of the time. 

To me, three things particularly stick out about individual teams from the tables above:

1. Minnesota is a weird team. It looks like the Golden Gophers are really just that good at offensive rebounding. I expected them to allow an extremely high percentage of transition plays due to crashing the boards, but it was actually the lowest of the top 10 teams at 36%.
2. Northwestern St. is the biggest cherry picker in the country. I haven't watched film, but the stats show that Northwestern St. takes a shot within 10 seconds of getting a defensive rebound 58% of the time. This was by far the highest percentage and might be a reason why Northwestern St. is the second best team in the Southland.
3. Bucknell ran a fast break once, just to see what it felt like. Yes, I think Bucknell is the most interesting team in the NCAA. Dave Paulsen's squad focuses on boxing out and holding teams to one shot. They only get out in transition on 14% of missed shots (not a typo).

For those of you statistically inclined, here are the scatter plots of the cherry pickers and non cherry pickers. You can see the r-squared values and how big of an outlier Minnesota is in all of this. Removing Minnesota increased correlation tremendously.

Cherry Pickers:

Conservatives: