There are pro basketball players who are deadly from the foul line. Steve Nash, for example, was the all-time best, making 90.43% of his free throws during 18 seasons in the NBA. Then there are guys like Ben Wallace and Deandre Jordan, who are among the worst, canning foul shots at a dismal 41%. According to some researchers, the shot with the highest possibility of success is the underhand -- or "'granny" shot -- which hasn’t been seen in the NBA since Rick Barry used it in 1980.
The key lies in the arc of the ball. Overhand shots tend to be flatter, so instead of easily dropping a ball that’s 9.5 inches (24.1 cm) in diameter through a rim that’s 18 inches (45.7 cm) wide with a high arcing underhand shot, the target becomes more of an ellipse. “That’s why these guys miss so much,” says Peter Brancazio, a physics professor and author of SportsScience: Physical Laws and Optimum Performance. By shooting underhand, he says, “there’s a far greater chance of making the basket.”
Putting the ball in the basket:
- Using trigonometry, Brancazio calculated that the optimal angle of the arc from the free throw line is about 45 degrees, plus half the angle from the top of the player’s hand to the rim (which accounts for a shooter's height).
- The granny shot benefits from a backward spin. “The ball bounces, but it doesn’t have a forward motion on it,” Brancazio says. This increases the likelihood that the ball will bounce into the basket, rather than ricochet away.
- The underhand shot is an easy-to-control upward pendulum motion. The overhand free throw involves separate movements of the wrist, elbow, and shoulder that can add errors, says Tom Steiger, who taught basketball physics at the University of Washington.
