Attention @THE_REAL_SHAQ: it's all about parabolas and backspin.
Free-throw success is also improved by adding a little backspin, which pushes the ball downward if it hits the back of the rim. The North Carolina State engineers calculated the ideal rate of free-throw backspin at three cycles per second. That is, a shot that takes one second to reach the basket will make three full revolutions counterclockwise as seen from the stands on the player's right side.
(via mr)