Exactly. I really don't feel that simply changing a grip will affect a fastball's movement per se. I've always considered 'movement' as more as 'tail' not sink. Some guys just have movement on their fastballs naturally due likely to physical things such as arm slot, release, etc., and for whatever reason lefties seem to have more than righties.I disagree a bit. I've taught a few kids to throw an "amatuer" two-seamer. (I say amatuer because I can't correlate it to a minor/major league level). The main imperative was pressure on the ball and length of the kids fingers to produce some movement rather than a straight even four seam.