The science of free throws

NBA players make about 75% of their free throws. Why isn't it higher?

Why don’t NBA players make more of their free throws?

Few things frustrate fans and coaches more than missed free throws. And it’s with good reason! Professional basketball players, you know, it’s their job to shoot a basketball. They get paid millions of dollars to do it. And many times a game, they are granted an opportunity to take a shot without any defenders. A shot so undemanding it’s been nicknamed a charity stripe. It’s not even a deep shot! It’s 15 feet, same as it is for high schoolers. There aren’t even many rules about it! Does a player have to keep both feet on the floor during the shot? No! A jump shot is totally acceptable (but never done). Is an underhand lob ok? Sure! (also never done). Is one eye required to be shut during an attempt? Obviously not!

It’s a gift, truly. Free points! About 20 percent of the points in a typical NBA game come at the free-throw line. It’s unusual in sports. A penalty shot in soccer at least has a goalie. It’s like if baseball players were granted intentional walks, but only made it to first base 80 percent of the time. Why don’t NBA players just practice this all the time?

There is a very simple answer that is quite reductive but also quite accurate and that is that NBA players are not robots. The deeper dive on this involves plumbing all sorts of mental tributaries, like the psychological impact of pressure and fatigue and overthinking. The bigger factor, I think, involves a concept called “motor noise,” the basic framework of which suggests that no movement is ever simple and is rather subject to minor perturbations and randomness (otherwise we would never have a sport called darts — we’ll get to this later).

But I want to leave all that aside and point out something that’s interesting about NBA free throw shooting and that is that it is remarkable consistent.

For the past five decades, or so, NBA players, on average, have made about 75 percent of their free throws.

In 1975-76, the first season after the NBA-ABA merger, the league average for free-throw percentage was 75.1 percent. The year after that: 75.1 percent. The year after that: 75.2 percent. In 1996-97, it was 73.8 percent. 2009-10: 75.9 percent. You get the idea.

There’s a glaring outlier to this strangely predictable run: In 2020, an 88-game stretch for 22 teams produced an average free-throw percentage of 79.2.

It was the pandemic-forged stretch in which games were played in a spectator-less arena known as the NBA “bubble.”

79.2! Considering the history of the game, it’s a miraculous figure, even for a relatively small sample size. Did NBA players spend their quarantine periods practicing free throws? Perhaps! But, alas, when arenas resumed filling up to capacity in 2021 and 2022, the free-throw percentages fell back down to 76.4 percent and 76.2 percent, respectively.

These numbers have been provided by Logan T. Markwell and fellow sports scientists Andrew Strick, Jared M. Porter, and Harjiv Singh from the University of Tennessee, UNLV, and the Orlando Magic, respectively, in a paper published in November. The authors proposed a reason for why this bubble-induced statistical anomaly might have been the case. It’s not about how much the NBA players practice their free-throws, but the way they practice them.

Professional basketball players, you know, they’re used to an audience. They generally don’t seem to mind performing in front of thousands of screaming fans. The sports psychological industry has devoted massive amounts of resources to bolstering players’ mentality so that they can essentially focus without falling victim to distractions from the audience. Of course, this is pretty much impossible, and fans have made it a mission to involve themselves — particularly during the free throws.

Please, put your shirts back on.

Because you’re not the reason NBA players miss free throws.

The reason that Markwell, et al., bring up is that players don’t practice in front of fans. Their practice conditions, therefore, are different from what they will expect in a game.

This is an important point. The specificity of practice and its mapping onto the in-game experience has been well-studied in the field of motor learning and cognitive psychology. In a nutshell, skills are better transferred when the practice conditions are more precisely like the conditions expected during a performance. Our cognitive representations of a task are so specific that researchers Luk Proteau and Ronald Marteniuk once found that people performed worse when they could use their vision to aim at a target after they’d been practicing doing it blindfolded. Seeing the target was detrimental if you’ve been practicing without it!

Basketball players practice free throws in an empty gym. The game, therefore, is not like how they practiced it. Players are trained to use mental representations and visualization techniques to take them back to the practice gym mentally to block out all the fan distractions. But this, imo, probably isn’t efficient. Perhaps a better method would be to practice while visualizing shooting free throws in front of thousands of screaming fans. Practice like your game conditions, not the other way around.

The evidence is in the bubble. When the games were played inside an empty gym, their competitive free throws became more like practice, and their percentages went up. When fans returned, the percentages dipped back down.

At Syracuse, Jim Boeheim was a rarity in that he used to conduct open practices, which fans could attend. Fans rarely showed up anyway. If they really wanted to help their players at the line, they’d show up and get loud during practice to better simulate a game situation. Trust me, the Orange could’ve used the help.

Free-throw calibration

Speaking of free-throw shooting percentages, one factor does seem to imply whether or not an NBA player is going to make his shot: if he has already attempted a free throw moments earlier.

In 2020, researchers in Cologne, Germany, analyzed more than 610,000 free throws from 1,098 players in NBA games between 2006 and 2016. They found that, regardless of fatigue, the success rate for the second free throw was uniformly higher than the first attempt. If the player was taking 3 free throws, then the success rate of the third attempt was higher still.

The researchers cited their findings as a confirmation of a 2019 study on expert dart throwers. In darts, a player makes three successive tosses, then goes to the board to retrieve the darts before a next player tosses, in a cycle of tossing and waiting. And, well, sure enough — among those experts participating in the 2017 World Darts Competition, the first toss was consistently less accurate than the next two.

Ok, so, why would this be the case?

The throwing of the first dart, or the first free throw, gives the performer a “visuomotor calibration” of what he or she needs to do. This might sound ridiculous for something as well-rehearsed as a free throw! But it’s not. Elite skill relies a great deal on registering the feedback that your motions are offering (the ball’s feel off the fingertips, the position of your shooting form, etc) and fine-tuning constantly to optimize performance given certain conditions (how you’re being defended, your fatigue level, your sweat output, etc).

It’s the case even in darts, a skill already so finely tuned one would think it cannot be optimized further. But the researchers found that even the world’s best dart players routinely missed their targets vertically on the first toss. Their improvement vertically on the second toss was “consistent and conspicuous,” the researchers wrote.

Why would “re-calibration” be necessary in the first place? Don’t these players constantly practice these things?

Recall what I said earlier about the “cycle” of dart tossing. In those slack periods in which a player has finished his or her tossing, her visuomotor system is doing something … other than aiming at a target. Therefore, when it’s their turn again, the brain needs to “recalibrate” what it’s been trained to do. That’s why the first shot is generally less accurate than the succeeding ones.

The scientific term for this is the “warm-up decrement,” coined by Jack Adams in 1975, and I’ll probably save the bulk of the research on this for another post. But the main thrust of this theory is that the motor system has a lot that’s required of it, and even just walking around or attempting another task can mess with the delicate skill of an elite performer. Returning to that elite level of skill requires a calibration, a warmup. The first shot is essentially a warmup.

Can you calibrate ahead of time so that your first shot becomes more accurate?

Theoretically, sure! The researchers, however, don’t offer any suggestions on this, other than to recognize that re-calibration is necessary to achieve peak performance.

Whether that can be achieved through visualization, or mental imagery, or has to be paired with a motor element and feedback — I don’t really know. Maybe you have some suggestions for further research on this?

Links

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References

Markwell, Logan T., et al. "The Effects of Spectators on National Basketball Association Free Throw Performance." Journal of Motor Learning and Development 1.aop (2023): 1-12.

Phatak, Ashwin, et al. "Better with each throw—a study on calibration and warm-up decrement of real-time consecutive basketball free throws in elite NBA athletes." Ger J Exerc Sport Res 50 (2020): 273-279.

Wunderlich, Fabian & Heuer, Herbert & Furley, Philip & Memmert, Daniel. (2020). A serial-position curve in high-performance darts: The effect of visuomotor calibration on throwing accuracy. Psychological Research. 10.1007/s00426-019-01205-2.