The curve and the fast one are important; the change of pace and the other trick deliveries are great but they're not worth a plugged nickel unless you have control to go along with them. And by control I don't mean the ability to put the ball over the plate somewhere between the shoulders and knees. I mean the ability to hit a three-inch target nine times out of ten, the sort of control that lets you put the ball in the exact spot you want it, and to play a corner to the split fraction of an inch.