Rebounding, Positionality and Transition Play

Following up from Justin’s earlier post about the difficulties in forecasting individual effects on team rebounding as well as some earlier work I’ve done which suggests the battle is really over about half the available rebounds[1. With only two seasons of SportVU data, it’s premature to make hard and fast pronouncements about upper and lower bounds, but I’d guestimate about 50% of missed shots are going to be rebounded uncontested by the defense while about 5% are going to wind up bouncing straight to an offensive player. The battle over the other 45% is where the real action lies. Splitting the difference on that 45% evenly, the league average offensive rebound rate on missed field goals would be 27.5%. In 2014/15, the NBA as a whole had an offensive rebound rate of 26% on missed shots from the floor, so I feel I’m at least in the ballpark here.] I wanted to point out what appears to be something of a paradox, and that is guard rebounding.

In terms of helping team rebound rate[2. That is not just pushing the same rebounds around amongst the five on the floor as Justin discussed earlier today and I alluded to here.], uncontested defensive rebounds are worth around half of other types of rebounds. Perimeter players who secure large numbers of rebounds tend to gorge themselves on these freebies. So, guard rebounding is gaudy from a statistical standpoint, but maybe not actually that helpful. Unless it is.

The benefit of a defensive rebound is two-fold. For one it ends the opposition’s chance to score. Additionally, grabbing that board might key a fastbreak. Playing on the break is good for all the usual notions about getting quality open looks against a not-quite-set defense.

And herein lies the conundrum – it appears on first pass that rebounds by guards are more likely to start a fastbreak than those by wings and so on. Controlling for location of the original shot (because this also greatly influences the likelihood of transition play), we can see that no matter where on the floor a shot is taken from, the smaller the player who grabs the defensive board, the more prevalent a fast break:

In fact, the above can be simplified somewhat into shots taken from inside the paint and outside:

So which is it? Are guard rebounds less valuable because they tend to be the freebies that anyone on defense could collect, or are they more valuable because they lead to fastbreak buckets? I don’t have that answer as it’s another one of the those things where there is a push and pull in opposite directions which makes the overall effect that much harder to suss out.