Here’s a basic basketball question: if a player misses a 3-point shot from the left corner, where will the rebound go? The answer to this question has obvious competitive advantages, regardless of whether you are playing a pick-up game at the park or you are playing in the gold-medal game of the Olympics.
So what’s the answer? Where do missed corner 3′s end up? Thanks to SportVu data, we can now answer this question. I plotted and analyzed the rebounding locations for over 26,000 missed shots from the 2011-2012 NBA season, including about 1,800 missed corner 3′s. When an NBA player misses a corner 3 from his left side, the rebounds go here:
The spatial structure above is undeniable; missed corner 3′s go to the opposite side much more frequently than they ricochet back toward their origin. In fact, the most common location for a missed corner 3 rebound is just south of the college “low block” on the opposite side. Rebounds land there about 5X more often than they do at the corresponding location near the other block.
So, where do rebounds happen? It depends. It depends on shot location, rebounder positioning, and rebounder athleticism. In this article I examine the interactions between shot location and rebounding location in the NBA. I think I’ve found some interesting results that are likely to change the ways you think about rebounding and boxing out.
This interactive graphic reveals** where rebounds go according to shot location. As you mouse over different sections of the court, the rebounding signatures change:
** if you are on an iPad, iPhone, or some other device that does not support Flash, this will not work for you. Please check back from another device. I’ve also included other graphics below that will work for you non-Flash types.
I will provide much more detail later, but here are 4 main takeaways:
1. Rebounds go to “the other side” – when a field goal is attempted from the baseline or wing areas and it misses, chances are the rebound will occur on the opposite side of the rim. How much to the other side depends on where the shot was taken (shot angle, shot direction).
2. Offensive rebounding percentage for jump shots hovers between 20 and 25%; however, missed shots closer to the rim such as floaters, put-backs, and layups result in a much higher offensive rebounding rate.
3. There is a direct relationship between shot distance and rebound distance. The longer the shot attempt, the further away from the rim the rebound is likely to occur. The corresponds with the idea that 3-point shots often result in “long rebounds”.
4. In the NBA, 3-point shots are much better options than midrange shots for 2 reasons: 1) The decreased FG% is more than compensated by a higher reward in terms of points per attempt, and 2) not only do made 3-point shots obviously result in more points, missed 3-pointers are more likely to result in offensive rebounds than missed midrange jumpshots. Midrange jumpers kill possessions more and result in points less.
The microgeography of missed field goals:
About 65% of the time an NBA player takes a jumper, a future rebound gets its wings. As a result, everytime a shooter rises to take a jump shot, other players begin “fighting for position” – but, where should they fight to get?
First of all, we already know that most rebounds occur near the basket, which is one main justification for the common coaching tenet of boxing out: keep your opponent further away from the rim, and you’ll increase your chance of acquiring a rebound. That may seem obvious, but since the origin of the rebound is almost always a ricochet off some part of the rim/backboard apparatus, and a rebound’s trajectory is generally toward the paint, it makes sense that the person closest to the rim apparatus at the time of the ricochet has the best chance of grabbing the ball.
But positioning wisdom involves more than distance; it involves direction as well.
This concept is best illustrated with baseline shot attempts. Let’s look at the relationship between rebounding locations and shot locations near the baseline. We’ll begin with longish midrange baseline shots. The following image shows where rebounds go when these shots are missed. The yellow highlighted area is the shot zone; the red area is the “rebounding epicenter,” or the area on the court where rebounds are most frequently collected when shots are missed from that shot zone.
As you can see, when an NBA player misses a shot from the baseline, the rebound most frequently occurs on the opposite side of the rim; for visual confirmation, here’s the rebounding signature for baseline shots on the opposite side:
Check out the rebounding epicenter here: when a player misses a longish midrange baseline shot, rebounds are most commonly grabbed at the edge of the “restricted area” on the opposite side of the rim. When we step back to the corner-3 zones, we see the exact same effect – the only difference is that the rebounding epicenter occurs a bit further from the rim… longer shots beget longer rebounds, you guys.
You can see that the rebounding epicenter for missed corner threes is clearly outside the restricted area, and very close to the “low block” on a college basketball court.
Let’s contrast that with some other midrange shots, which result in very different rebounding patterns. When we examine rebounding signatures for shots closer to the middle of the floor we see the epicenter venture back inside the restricted area. The whole “opposite-side-of-the-rim” effect still applies, but is much less drastic; compared to baseline attempts, centralized jump shots beget more centralized rebounding signatures.
Using the information here we can contemplate the confluence of FG%, points per attempt, and offensive rebounding %; we can begin to think about shot selection in the NBA from a more informed plateau. With this in mind, the midrange jumper is the least efficient shot in basketball, it results in the fewest points and also kills possessions at the highest rates. Does this mean midrange shots are always foolish? Of course not, many of the NBA’s best teams like Boston, Miami, and Oklahoma City effectively use the midrange shot on a frequent basis. Regardless, league-wide the efficiency of a shot cannot simply be judged by its expected point total; we must also consider the offensive rebounding rate, which determines whether a given possession ends or whether the offense gets another try. With this in mind, getting shots near the rim has a double-benefit: 1) close shots have a higher FG%, and 2) missed close shots more commonly result in second and third chances for the offense.
I wanted to thank the nice folks at Stats Inc., especially Brian Kopp and Ryan Warkins, for their help with this project. Thanks to SportVu data we can now analyze basketball in exciting new ways. As the NBA enters its own version of the ‘Big Data’ era, we all benefit. Optical tracking data will enable analysts to understand basketball and communicate about basketball in transformative new ways. This data will not only feed the addictions of NBA geeks like me, but they also will help everyone learn a little more about basketball basics. There is an exciting new opportunity for analytics to go beyond helping one team beat another team, but to help the community at-large acquire fundamental knowledge about the game we all love.