I was hoping spin could be a temporary force and some physics guru could tell me how to get spin to increase speed using laces to soar until the spin died out. I'll go back to the concession stand and break the bad news to all the other dads. The moral of this story is to use movement pitches and not rely on a fastball. Also, speed isn't everything, as I eluded to at the beginning.I wont get into the whole rise ball rises or drops less than gravity would dictate argument in this thread...
But either way, there is no acceleration involved. No engine or source of force being applied to directly to the ball - no acceleration. Laces/etc may effect direction or break but it cannot effect acceleration positively - only negatively. Laces do not provide energy.