http://www.cyberslugger.com/pitching.htmlThe concept then of the changeup is to let the ball come off your fingers. Your wrist then should be in the lead (remember high-five with fingers pointing up and not at the batter) when you begin to release the baseball. As your hand comes through behind your wrist, the ball is forced away from your body by your fingers. The key here is to make sure you have a down and away motion with your arm. This causes the ball to have a heavy backspin as well as to break away from a right-handed batter assuming the pitcher is right-handed.
This backspin on the ball creates negative force and slows it down as it cuts through the air. Key: Remember to keep your arm speed the same as your fastball. You DO NOT want to slow your arm speed down to slow the ball down. The grip can be tricky and is important for accuracy and effectiveness. Whether you use a circle change, a three finger change or a palm grip, the ball must lie or rest on the balls of your fingers (meaning where your fingers are attached to your palm). You dont want to have the ball jammed up in your hand because that makes the pitch harder to control. Keeping your pinky finger on the side of the ball helps immensely. Always concentrate on letting and feeling the ball come off the fingers in a down and away motion. Use a two seam grip for more downward movement.