The Shadow to Balance Drill is highly effective in getting pitchers to "learn" the all-important first stages of the pitching motion – getting from the stance to the balance position in a controlled and balanced manner. Because no baseball is used in this drill, a pitcher can practice this beneficial exercise on a daily basis, regardless of when he is pitching during a particular week.
When you start actually throwing the curveball, I recommend getting the feel for ball release first and working backwards from there. So start off real light, about 15-20 feet from your target. I usually like to start guys off facing their target, feet shoulder width apart, toes pointed forward. You can even start out on your knees to take the legs out of it completely (forces you to keep it light). And just get the arm up with that good hand and wrist position, and work on tossing/flipping the ball with good forward spin.
One common situation arises when a pitcher faces a “same-handed batter” – a righty pitcher matched up against a right-handed batter, or a southpaw against a left-handed batter. In these matchups, a fastball breaks toward the batter, while sliders and curveballs break away from the batter. If the pitcher aims his slider toward the outer half of the plate, it tends to move farther and farther away from the batter as it approaches him – perhaps ending up far outside the strike zone.
One of the biggest issues pitchers have when they begin throwing a curve is changing their fastball mechanics. Don’t! Throw the curveball, or any other pitch, using the same arm slot and arm speed as your fastball. The only thing that changes is wrist and forearm angle. With the curveball your wrist and forearm angle look like a “karate chop”. To get an effective rotation on the ball, released the ball late. The curve will squirt or hang when you release it early or you don’t keep your glove in front of you at release. I explain this in greater detail in the you tube video below.