If you ask me, it's an art. On ESPN.com, Buster Olney examines lateral movement on pitches, citing Roy Halladay as a prime practitioner:
He has so much movement on his pitches that he simply aims the ball down the middle, and then allows the natural movement of his refined pitches to take the ball to the edges of the strike zone.
When Doc's fastball is straight, as it was in Anaheim, he's just another good pitcher. I expect that he's made the necessary adjustments, and the D-Rays will find it difficult to make solid contact tomorrow.
https://www.battersbox.ca/article.php?story=20030805053031999