Here's what MythBusters think of it:
http://www.youtube.com/watch?v=A1VClnk3l-kHere is what a professor of systems and engineering says:
"The Rising Fastball — For years batters swore that some pitchers could throw a rising fastball that would "jump" a half foot as it crossed the plate, making it hop over the bat. But this isn't possible, Bahill says. Even the greatest pitchers can't violate the laws of physics. Once a ball is thrown, it follows a smooth trajectory. Physics simply doesn't allow abrupt jumps in that trajectory.
So what's happening? "The batter is using the wrong mental model," Bahill says.
Batters divide a pitch into thirds. The first third is sensory gathering, the second is computing, and the third is swinging. So a pitcher throws several 90-mph fastballs and the batter develops a mental model and reaction to this speed, Bahill says.
Then the pitcher slips in a 95-mph fastball. During the sensory gathering segment of the pitch, the batter doesn't see anything different. He calculates where the 90-mph fastball would go and swings at that spot. But the 95-mph fastball has a flatter trajectory. It doesn't drop quite as much from the pitcher to plate because it's going faster.
"When the batter starts to swing, he takes his eye off the ball to look at the predicted bat-ball collision point," Bahill says. "When the ball comes back into his view, it is higher than his mental model predicted and he sees it 'jump' higher than where he calculated that it would be."
A link to the article:
http://uanews.org/node/2845One more link for now:
http://www.mvpmods.com/index.p...d223d18f3044c5e87608