How Do NBA Stretch Bigs Affect Team Defense?
There's a league-wide trend in the NBA of offenses going smaller. As we gather more and more data about offenses, it's becoming clear that the more shooting you have, the better (and more efficient) your offense will be. I know, this seems obvious.
Since this is the case, it's obviously advantageous to have four shooters from outside - where the shots are valued more highly - as opposed to just three. And so the stretch big was born.
While some teams are still rejecting the trend - most notably, the Clippers and Warriors - many more are starting to adopt the notion of having a stretch big at a frontcourt spot. The advanced analytics support this as well. Just look at how a stretch big affects the offense of their fellow big.
However, the biggest knock on these players is defense. The type of big that is both a stretch big and a rim protector - Serge Ibaka is on his way, for example - is possibly the rarest of all NBA forms. Most often, there is a trade-off. You take the offensive gain from a stretch big, and deal with it on the defensive end.
But we are still learning about this. The idea of a stretch big isn't brand new to the past couple years, but it's always been in the minority. Now that it's legitimately trending, our sample size is becoming big enough where we can start to evaluate data. So, how exactly do defenses perform with a stretch big on the floor?
Note: the table below shows the stats of the opposing offenses with and without the stretch big. For example, opposing teams scored 1.058 points per possession with Josh McRoberts on the floor, and 1.045 with him off the floor. The data is courtesy of nbawowy.com.
PPP = point per possession
TS% = true shooting percentage (accounts for three-pointers and free throws)
%0-3 = percentage of shots from 0-3 feet
FG%0-3 = field goal percentage from 0-3 feet
%4-9 = percentage of shots from 4-9 feet
FG%4-9 = field goal percentage from 4-9 feet
| Stretch Big ON/OFF | PPP | TS% | %0-3 | FG%0-3 | %4-9 | FG%4-9 |
|---|---|---|---|---|---|---|
| Josh McRoberts ON | 1.058 | 53.3% | 28.9% | 59.3% | 12.7% | 35.7% |
| Josh McRoberts OFF | 1.045 | 52.3% | 31.3% | 58.7% | 14.3% | 34.9% |
| Kevin Love ON | 1.066 | 55.4% | 30.5% | 67.4% | 13.5% | 40.3% |
| Kevin Love OFF | 1.060 | 54.0% | 32.6% | 62.7% | 14.3% | 37.9% |
| Ryan Anderson ON | 1.129 | 55.9% | 32.7% | 63.7% | 12.7% | 40.2% |
| Ryan Anderson OFF | 1.100 | 55.8% | 33.7% | 64.0% | 13.2% | 37.5% |
| Dirk Nowitzki ON | 1.086 | 56.0% | 30.8% | 65.1% | 13.9% | 40.6% |
| Dirk Nowitzki OFF | 1.089 | 55.3% | 31.6% | 65.4% | 15.0% | 36.9% |
| Channing Frye ON | 1.070 | 54.4% | 31.5% | 62.2% | 15.5% | 39.3% |
| Channing Frye OFF | 1.068 | 53.8% | 33.1% | 63.0% | 16.3% | 37.6% |
| Terrence Jones ON | 1.095 | 53.5% | 31.3% | 63.4% | 14.7% | 35.9% |
| Terrence Jones OFF | 1.047 | 52.2% | 27.1% | 61.6% | 15.0% | 36.5% |
| Spencer Hawes ON | 1.131 | 55.7% | 26.7% | 64.3% | 11.3% | 38.0% |
| Spencer Hawes OFF | 1.073 | 54.1% | 27.9% | 63.7% | 13.1% | 39.3% |
| Avg Difference (ON - OFF) | + 0.022 | + 1.0% | - 0.7% | + 0.9% | - 1.0% | + 1.4% |
The data shows that opposing teams scored less, in terms of point per possession, with the stretch big off the floor. This backs those who claim that defenses are worse with stretch bigs. However, the difference isn't large for some of the stretch bigs, and in the case of someone like Dirk Nowitzki, the Mavs defense was actually better with him on the court.
The most interesting finding here is that opponents almost always shot less frequently around in the rim and in the paint with the stretch big on the court. The field goal percentage goes the other way, however, with teams hitting a higher rate from that area, despite shooting less frequently.
So why do teams shoot less frequently from inside with a stretch big on the court? It makes sense that teams would shoot better from inside, as they don't protect the rim as much. But I would have expected the data to show that opponents shot better and more frequently.
This could be an interesting study in the future. My guess, and it's purely speculation, is that there is some correlation of stretch bigs to lateral quickness. Since they can't protect the rim, the opponents shoot better once they get inside. But, the opponents don't get inside as much due to the increased quickness on the perimeter.
If that is the case, then perhaps stretch bigs can bring their own advantages to defense - just ones that we hadn't quite realized before. And if you can combine them with a rim protector, then there is a defense. Stretch bigs can use their lateral quickness to keep players out of the protected area, while their rim protector counterpart helps clean up any mess.
There is still a lot to learn about this subject, and the game will continue to adapt. However, after now studying the effect of stretch bigs on both offenses and defenses, I still stand strong in my belief that they are one of the most valuable commodities in the modern NBA.
