I don’t think that it makes much difference how one grips the ball. When I was learning the pitch, my coach—an active major league pitcher who threw a very good one—demonstrated the grip, which was very much off-center, with the index and middle fingers very close together and the middle finger just touching one seam. The key is the wrist action; he told me, “Throw it like a curve, but roll your wrist, don’t snap it.” I threw my curve with a karate-chop wrist snap, so he told me to simply ease up on it. He demonstrated this, then handed me the ball and told me, “Go ahead—try it.” I got the hang of it in about ten minutes, but it took me some nine or ten months to really get that pitch down cold, which was what I did.
I was, by the way, a natural sidearmer, and I was using the crossfire a good deal—in fact, I fell so in love with that delivery that I used it with just about everything I threw! I found that it gave me twice as many pitches as I had in my rapidly expanding arsenal, and the batters used to have conniption fits right and left because they couldn’t hit it to save themselves.—My coach showed me how I could change up on that pitch, always being sure to throw everything with the same arm speed and the same arm action. 8)