Learning How To Throw A Sinker Ball
One of the most effective pitches in all of baseball is the sinker ball. Those who master throwing the sinker can be successful using just that one pitch. It is safe enough on the arm to be taught to youth baseball pitchers.
The sinker ball is a pretty easy pitch to learn because it is thrown like a fastball. There is no twisting of the wrist like a curve ball or slider. Throwing a sinker also reduces the chances of shoulder injuries and rotator cuff problems.
The sinker ball is most effective at high velocity (90 - 95mph), but it can still be effective at lower speeds if complemented with other pitches. Sinker ball pitchers tend to have a higher ratio of swinging strikes, ground balls and fewer home runs because the sinker is thrown down in the strike zone.
To learn how to throw a sinker you need to position the index and middle fingers along the two seams at their narrowest part (the two fingers should actually be parallel, or on top of the seams). Position the ring finger and pinkie on the side of the ball. Position the thumb on the opposite side of the ball, between the two seams where they are closest.
Now that you have the sinker ball grip, start your windup and release the ball as you would a fastball. Don't twist your wrist. The object is to release the ball with the index and middle finger on top of the ball. When you release the ball "push down" with your wrist. Simultaneously push down on the ball with your index and middle fingers, pushing harder with the index finger. The ball will sink sharply.
When releasing the sinker ball, target the ball between the batter's waist and knees. If you throw it up in the zone it won't sink as much and it will end up in the batter's sweet spot. Throw it too low and you risk throwing it in the dirt and increasing the chance of a wild pitch. Follow-through the pitch as you would when throwing your fastball.
Once you have learned how to throw a sinker you can adjust the position of the index and middle fingers to get movement to the right or left. For example, if you are a righty pitcher and you want the sinker to move down and away on a righty batter, position the index and middle fingers between the right seam. The release is the same, index and middle fingers on top of the ball. The only difference is your fingers will be "off-centered". This will put a natural spin on the ball that results in the ball moving down AND away from the right-hand batter. To make the sinker move down and in on a right-handed batter do the same on the left seam.
The sinker ball has become very effective in recent years because hitters are looking to hit the long ball instead of just making contact. The result is that sinker ball pitchers have become more effective with more strikeouts and more ground balls.
The benefit of learning how to throw a sinker is you're less prone to wrist and elbow injuries. In fact, learning how to throw a sinker will also help you avoid shoulder injuries and rotator cuff problems.