How to throw a screwball like Pedro Martinez
If the screwball is so great, why aren't more pitchers throwing it?
The screwball, or fadeaway pitch, is basically a backwards slider. It breaks in on right handed batters facing right handed pitchers. There are only a few pitchers in the majors now who throw screwballs on a regular basis, including Jamie Moyer, Dallas Braden, and Pedro Martinez until he officially decides to retire. Daisuke Matsuzaka throws a gyroball that is very similar to the standard screwball.
So why should you throw a screwball if it's not very popular? Well, BECAUSE it's not very popular! If not a lot of guys throw the pitch at various levels of baseball, that means few hitters are seeing the pitch. That means if you can master it you'll be baffling hitters all game. Let's take a look at how the pitch is thrown and see what techniques you can use to improve your screwball.
How to throw a screwball
There's a lot of different information out there about the grip you should use when throwing a screwball. My preferred grip is similar to a 2-seam fastball grip, with the index and middle finger in between the seams where they are closest and the thumb underneath the ball. The one difference is that I like to shift the ball slightly to the right in my hand, so my fingers and thumb are favoring the left side of the ball and my index finger is on the seam instead of next to it. Your ring finger should not put too much pressure on the ball with this grip. Some pitchers might even decide not to curl their ring and little fingers into their palm and will instead have them stiff and straight and not touching the ball. This can be effective, but it will also give your pitch away to the batter.
There's some controversy about how the screwball is thrown. I'm going to tell you one thing, but your coaches might tell you another. I've found that my method was quite effective for me. What I like to do is pre-load the arm. What I mean by this is that I have my wrist cocked at an odd angle when I'm about to begin to bring my arm through. The thumb is on the inside (towards the body) while the index and middle finger are on the outside (away from the body). As my arm moves forward I pronate my wrist, which means I turn it counter-clockwise. Just thing of the motion you'd use to loosen a screw with a screwdriver. You use that motion and let the ball release, with the right side of your middle finger (if you're a righty) being the last part of your body to have contact with the ball.
When watching this from behind the right-handed pitcher, it will appear that the ball pops slightly upward out of your hand and then dives down and in on the right handed batter.
Here's a video teaching the screwball
When to throw a screwball
The screwball can be used whenever a changeup would be used. It should be used more often on opposite handed hitters. For instance, if you're a righty you should use it more on left-handed hitters. Why? Because the pitch will move away from them, just like Mariano Rivera's cut fastball. Why do you think Mariano is one of the only right-handed pitchers in baseball who does better against lefties?
Pedro Martinez threw a screwball with devastating results. It was only slightly faster than his changeup, but with a lot more bite away from the lefty hitter.
The list of pitchers who have mastered the screwball contains many Hall of Famers, including Christy Mathewson, Carl Hubbell, Warren Spahn (winningest southpaw of all time) and Juan Marichal.