This book was recommended to me by an attendee of the Sports Vision course and I found it extremely insightful into not just the visual aspects of baseball but anything that involves a ball of any sort.  The book helped to dissolve many of the misconceptions that have existed relative to curve balls or the possibility of a "rising" fastball.  The physics of curve balls and the paths they travel and the science of how a rotating ball, from baseballs to golf balls to soccer balls, was described in easy to understand concepts.  The flow of air around a baseball is much like the flow of air over and under a wing.  The rotation of the stitches creates differential points of where the flow shifts from laminar flow to turbulent flow.  The asymmetry in this creates lateral forces that act to move the ball away from the simple hyperbolic arcs that would exist secondary to gravity only.  It is these asymmetric forces that are the basis for these shifts and Watts and Bahill do a great job explaining them.

Here are some facts about an 80-mile an hour curve ball.  It moves 2.1 feet laterally during its 60 feet 6 inch path.  Only .52 feet of that occurs in the first half of the path to the plate.  •It moves 0.058 feet in the first 10 feet. •It moves 1.45 feet in the last 10 feet!  They also explain a little about knuckle balls.  Knuckle balls with very low spin rates, for example, 3 rpm, has typical lateral displacement of 2 feet. The distance a knuckle ball moves is independent of velocity.  Thus, it is better to throw a knuckle ball fast as it will still have all that lateral movement occurring in a shorter period of time.