“Regardless how the pitch is gripped, the purpose of the knuckleball is to avoid the rotational spin normally created by the act of throwing a ball. In the absence of this rotation, the ball’s trajectory is significantly affected by variations in airflow caused by differences between the smooth surface of the ball and the stitching of its seams. The asymmetric drag that results will tend to deflect the trajectory toward the side with the stitches.

Over the distance from the pitcher’s mound to home plate, the effect of these forces is that the knuckleball can “flutter” or “dance” or “jiggle”, or actually curve in two opposite directions over its flight. A pitch thrown completely without spin is actually less desirable, however, than one with only a very slight spin (so that the ball completes perhaps between one-half and one rotation on its way from the pitcher to the batter). This will cause the position of the stitches to change somewhat as the ball travels, and therefore the drag that gives the ball its motion, thus making its flight even more erratic. Even a ball thrown without rotation will “flutter” somewhat, due to the ‘apparent wind’ it feels as its trajectory changes throughout its flight path.”

Also a great resource for those wanting more info on how to pitch this puppy: http://www.oddball-mall.com/knuckleball/k101.htm.

Brian, I am pretty sure that your list of current major leaguers is accurate. I saw Ryan Jensen pitch for the Royals in 2005, but he had gone away from throwing the Knuckler by then. Maybe he should go back to throwing it, since he has not played since the Royals in 05.

Also, I want to mention three former major leaguers that pitched this beautiful pitch.

Wade Boggs (A Hall of Famer). He didn’t get in the Hall by pitching, but when he did pitch, it was his favorite pitch. Pitched twice in his career (2.1 INN). Threw 16 knucklers in a 17 pitch inning in 97.

Then there is the Niekro brothers, Joe and Phil who 487 wins as knuckleball throwers. Joe is in the Hall of Fame.