The split-finger, also known as the splitter, is deceiving because it appears to be a fastball; however it drops or fades down at the last second as it nears the plate.
The splitter is 4-7 mph slower than your fastball.
A common misconception about this pitch is that it is a fastball; it's a changeup.
The hardest part about this pitch is the grip, simply because it is one of the only pitches you throw when the thumb and middle finger don't split the baseball in half.
To grip the split-finger place the index and middle finger on different sides of the two seams; "splitting" your two fingers.
The V in the split takes the place of the middle finger.
The further you split your fingers, the slower the ball goes.
The pitch is thrown just like a fastball.
The split-finger is not meant to be thrown for a strike, but to upset the batters timing or prompt a swing and miss.
Therefore, it is best to throw this pitch when you are ahead in the count or you feel the batter is anxious.
It makes a great strikeout pitch.
At release you have to make sure that you don't twist your wrist.
This is when the pitch can be dangerous for pitchers to throw.
To avoid twisting your wrist at release, make sure that you grip the ball correctly by placing your thumb directly under the split fingers.
There's not much to explain about the Split-Finger because there really isn't much to it.
Remember to keep your fastball mechanics with a proper grip and it won't take you long to learn how to throw it.
You will hear many coaches say that the split-finger is very hard on the elbow.
They are right.
However, most pitchers don't grip the ball correctly and twist the ball at release as mentioned earlier.
Once you learn the correct pitching technique it isn't a problem at all.
Split-Finger Tip: Don't overuse this pitch.
A good ratio would be to throw the splitter 15-20 times out of 100 pitches.
Famous pitcher's who throw this pitch very well are Curt Schilling, Roger Clemens and John Smoltz.