Overview
The curveball uses topspin to generate sharp downward movement. With a speed differential of 20-30 km/h from the fastball, it disrupts batter timing through dramatic velocity change. In NPB, Kimiyasu Kudo's curveball was iconic, pairing 130 km/h fastballs with curves around 100 km/h to keep hitters off balance. Curveball variants include the drop curve with steep vertical break, the slurve with lateral movement, and the power curve thrown at higher velocity. Tracking data now quantifies spin rate, spin axis, and movement, enabling objective evaluation of curveball quality. MLB has seen a curveball renaissance, and NPB pitchers increasingly feature high-spin power curves as primary weapons.