[MrUmpire]

Originally Posted by Dave Reed

From Gameday: PFX vs. BRK and Pitch Types:

"Pitch-f/x" is the distance between the location of the actual pitch thrown over the plate, and the calculated location of a ball thrown by the pitcher in the same way, with no spin. Or, in more common terms, this is the amount of "movement" the pitcher applies to the pitch.
Notice that the trajectory with "no spin" is slightly diferent than a trajectory in a vacuum, because in vacuum the ball wouldn't slow down on the way to the plate. Pitch-f/x calculates the trajectory including the drag which slows down the ball. The drag is in the direction opposite the instantaneous direction the ball is traveling, so it assumes that there are no aerodynamic forces are pushing the ball perpendicularly to the direction of the ball.

So, when a pitcher throws a 100mph pitch with a pitch-f/x of +12, it means that the pitch only fell about 3.5 feet on its way to the plate, rather than the 4.5 feet it would have fallen if it had no spin at all. \

So, SAUmp is now posting evidence to support the fact that fastballs do not rise. Who said people can't change?