At the MIT Sloan Sports Analytics Conference in March, writer Kirk Goldsberry gave a talk called “Beautyball: Using Analytics to Build Beautiful Games”. Goldsberry focused on the evolution of the NBA in the past decade and how the NBA has moved more towards two extremes for shot selections-a shot within 5 feet or a three pointer. As I noted in my last post, this trend has especially followed for All-Star level guards, but it has also been true for the league as a whole. Just in the past 10 seasons, the average number of threes attempted by a team in a game has risen from 17.7 in ’08-‘09 to 32.0 this season. To put this revolution in perspective, it wasn’t until ’14-’15 that a single team averaged more than 32 threes attempted a game (Houston Rockets at 32.7). The next closest team was the Cavaliers at a mere 27.5. Interestingly, the Rockets actually decreased their average and fell below 32 threes attempted. It wouldn’t be until ’16-’17 that more than one team averaged more than 32 threes attempted (Rockets, Cavaliers, Celtics). Two years later, 15 teams are averaging 32+ threes attempted. The 3-point revolution might just be getting started in the NBA, and one must wonder what that means for the midrange shot.
The premise behind the three-point revolution rests in the idea that you get more points per shot (PPS) from the three-point line than elsewhere on the floor. Let’s look at the numbers behind PPS from different distances on the floor.
|Area||Percentage (Mean)||PPS (Mean)|
|Less than 5 feet||61.2%||1.22|
The two extremes surely pop out at you. Within 5 feet, expected PPS is at 1.22, by far the highest PPS of the areas. The second highest PPS is from behind the arc, where the expected PPS comes in at 1.07. That’s .22 PPS higher than any other two point shot outside of five feet, so it makes sense that teams are shooting more and more threes. Goldsberry wonders if this continuing revolution is good for basketball as a sport and if not, what can be done. One proposition is moving the three-point line back. Currently, the line is 22 feet in the corners and 23.75 feet at the top of the key.
|Area||Percentage (Mean)||PPS (Mean)|
|Left Corner 3||38.6%||1.16|
|Right Corner 3||37.9%||1.14|
|Above the Break 3||35.0%||1.05|
Moving the line back might slightly slow down the three-point revolution but the numbers suggest it wouldn’t do that much. You can only extend the corner 3 so much before running out of room (unless the NBA extends the width of the court) and I’m skeptical how much an extension in the corners would really affect shot selection. An extension of the three-point line above the break might not have a significant impact either. Shots from 25-29 feet (deep threes above the break) have a PPS of 1.05, just .02 less than the 1.07 average for 3-pointers. Even moving the line back 1.25 feet would seem to make little difference and it’s hard to imagine the NBA moving the line back farther than 25 feet anytime soon.
So, what else can be done? Is the NBA destined to continue to push this revolution to its breaking point or is there another solution? One possible solution is to reverse the freedom of movement rule in the NBA. The freedom of movement rules allows players to move freely without being held or grabbed. This allows scorers and shooters coming off of screens to easily get to their spot and get a good look. While a reversal of this rule may very well lead to a decrease in scoring (something the NBA may not actually want), I am still skeptical of any potential impact it might have on three-point shooting. Any impact it has on three-pointers would likely translate to the midrange shot as well.
Another idea revolves around decreasing the width of the lane. The original lane was 6 feet wide, but it was widened to 12 feet before the 1951-52 season began because of dominant centers, specifically George Mikan. It was widened again to 16 feet, the width it remains today, before the 1964-65 season, again to limit dominant centers. A return to a 12-foot lane (the same width used by the NCAA and NAIA) would make sense and would likely slow down the three-point revolution some. I’m again skeptical how such a change might influence the midrange shot, but an argument could be made that the NBA is better off with an increase in paint scoring than three pointers. With a skinnier lane, it would be easier to score in the post and teams would likely begin to emphasize being patient and getting the ball to the block. This change makes the most sense for the NBA as it would allow for old school post players to return to dominance while not limiting the dominance of guards.
Before the NBA makes any sort of change though, they should (and undoubtedly will) wait. The three-point revolution is roughly 3-5 years young and it still remains to be seen how drastic it might get. What I expect to happen, like in any other basketball revolution, is for teams to adjust. The Milwaukee Bucks, with the best defense in the regular season, provided a glimpse of this for us. Milwaukee was first in the league in opponent points in the paint (42.2 per game), taking away the most efficient shot. They interestingly did not have great percentages compared to other NBA teams when it came to three-point defense, but they did force the most above the break three-point field goal attempts (28.4 per game-2 more than the number two team at 26.4). The Bucks understand that they really don’t want you shooting threes at all, but if you’re going to shoot them, they’re going to make you shoot them from then least efficient zone behind the arc. The only way for the league to return to a “normal” number of midrange shots is for defenses to adjust. The ideal defense would chase shooters off the three-point line but force them to pull up before getting to the rim. Teams have more data and are smarter than ever and I would bet on them to make the necessary defensive adjustments to slow down the revolution. Before the NBA goes about making any rule change, let’s see what adjustments teams can make.
All stats courtesy of stats.NBA.com as of April 29th, 2019.
For further reading, check out Kirk Goldsberry’s new book, Sprawlball: A Visual Tour of the New Era of the NBA.