Another interesting article on the gyroball written by Jeff Passan on Yahoo. Will Carroll offers some explanation as well on BP Unfiltered including a NY Times link to an article written by Lee Jenkins.
The Passan article seemingly causes more confusion as he says:
The theory behind the gyroball is this: When a baseball spins sideways, like a bullet, it should cut down on the amount of resistance on its path to the plate. Without the same amount of air resistance as a regular fastball, which rotates backward, the four-seam gyroball should not experience the same slowdown and look as if it's exploding toward the plate.This differs from the way the pitch was described by Alan Nathan a few months ago when he noted that the pitch would have a very small amount of break away from a right-handed hitter and using slightly different model would behave much like a cut fastball but with more drop. The confusion remains.
A perfect gyroball should be straighter than the crease on a pair of slacks.
"It doesn't move," Tezuka said. "It doesn't move at all."