A splitter (or split finger fastball) is thrown in much the same way as a fastball -- same arm action, same arm speed.
The difference, of course, is the grip.
With the fastball grip, you want to keep your fingers close together and the ball out in the fingertips to maximize run and velocity.
With a splitter grip, you want to split the seam, hold the baseball deeper in the hand, and throw it with a slightly stiffer wrist. It also helps to have bigger hands, which it why this pitch typically works better for older, more advanced pitchers.
What you don't want to do is get under the ball because it won't break down like you want - it'll hang up. Executed properly, the splitter should break down.
Here are a few more splitter grips submitted by readers of The Complete Pitcher...
Splitter grip (front view)
Splitter grip (side view)
The splitter is a great pitch when thrown properly and can be a nice compliment to other baseball pitches.
How do you throw your pitches? Post pictures of your pitching grips on my baseball pitching discussion forums.
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