Science of Baseball: The spin zone
Spin dominates the motion of a baseball, and pitchers change how a ball spins to throw different pitches. Viewed from home plate, a ball curves in the direction it spins, similar to how an airplane wing creates lift. A fastball has strong backspin to stay high, while a curveball has topspin to sink at the last moment. The rare knuckleball has almost no spin, which means the raised seams on the ball cause it to move unpredictably on its path from pitching rubber to home plate.