Throw a Dropball

. from the plate. This pitch should move at the same speed as your change-up.

Steps

Grip the ball exactly like a curveball, except do not tuck your ring and pinkie fingers in tightly. You should also hold the ball loosely like a circle change-up.
Throw and do not snap your wrist, roll it as you release the ball.
Remember this will take some practice, especially the wrist roll instead of a wrist snap.

Keep your motion the same to make the batter think it's just another fastball.
Use a 12-6 curveball. This ball just drops off the table just like the numbers on a clock, 12-6. No hitter will even touch this pitch. Practice for a couple of weeks. Another way is to take the ball and grip like a regular curve and keep your index finger up like a pointer also keep your middle finger on the inside of the seam. Throw like a curve by snapping the wrist and the ball should roll over your middle finger while your index finger,(pointed at the plate) will give the ball spin, this ball will drop at least {{safesubst:#invoke:convert|convert}} and if snapped hard enough should break at the last second.
Watch Barry on T.V. he will help and watch his form too, he has the best 12-6 there is, and the 12-6 should be {{safesubst:#invoke:convert|convert}} slower than a change-up.
For a sharp, late break- grip the ball like a Throw a 4 Seam Fastball, shift your fingers to the outside of the ball (your middle finger should be on the "horse-shoe" seams) grip the ball very tight in your palm and apply great pressure with your middle finger, and very little with your index finger. Tuck your elbow in very close to your body, and roll your wrist inwards. Don't throw this pitch sidearm.

Once batters figure out how to wait and see the drop, it will be easily hit. Don't throw it too often; every 1-6 pitches should be a drop ball.