A submarine pitch gets its description not from the outcome of the pitching motion, but from the pitching motion itself.
Assume a right handed pitcher for the sake of convenience of description. Think of a progression of pitches, all of which can be thrown with a number of different wrist movements and grip types. The extreme in one direction is an overhand pitch with the arm coming over at almost 12 o'clock. Then there is the 3/4 overhand pitch with the arm at about 1:30. There is a sidearm pitch, or the classic sidearm throw often done by shortstop. There the arm comes around at about 3:00 or even 3:30.
Now imagine carrying the path of your arm around the clock face until it hits an extreme of almost 6 o'clock. When you first see this pitch done, it looks illegal. It looks like an underhand pitch. It is not. The hand dives down like a submarine and then comes back up just a bit before the ball is released. The spin of the pitch (with proper supponation of the forearm on release) is such that the ball is rotating almost underneath. It's like doing an undercut of a tennis ball with the tennis racquet.
The "action" of any spinning pitch comes because you get a high pressure zone on the side that the ball is spinning from, and a low pressure zone on the side that the ball is spinning to. Whatever part of the clock face that your arm goes roughly determines the side of the ball where the high pressure zone is when your do a forearm supponation for the spin. This ends up being the side that the ball wants to go away from. Thus the ball will actually float up and perhaps slightly away from the side of the pitcher's throwing arm. Gravity and the pressure zones around the spinning ball actually are working against each other, with a slight side vector remaining. When the ball has its initial high spin, gravity is losing. As the spin slows from friction, gravity starts to win.
The final effect is interesting. Most batters end up swinging under the path of the ball and popping up. Those batters that hit it squarely but too slowly end up hitting grounders because of the way that that the spinning ball reflects off of the bat.
Want an entirely different science? The knucle ball is it!! Here one can almost parallel the claims of those who claim to do things differently. The knuckle ball really is different. The curve is caused not by the rotation of the ball, but rather lack of rotation which - combined with the stitches on the baseball - create a very unstable airflow around the baseball. The curve is completely unpredictable. Catchers have to use special mits to hang onto these pitches. They have a saying about how to catch one - wait until it hits the backstop and then pick it up.
Anyone who has ever read anything about the mathematical field of chaos can appreciate the knuckleball. For a good start on that subject, read the book Chaos: the making of a new science by Glick.
Complex? Yes. Difficult to explain? Only if you lack the language, lack the understanding of science, or have a hidden agenda.
[This message has been edited by Bill Glasheen (edited 04-09-99).]