It don’t mean a thing if it ain’t got that spin
You would think this would be self-evident but apparently it’s not, so I bring it up here.
There are two things that make a pitch move — the direction of the spin and the speed of the spin. You need to have both in order for the ball to do what it’s supposed to do.
Still, I am amazed at how many times I will watch a pitcher throw a “curve ball” or a “drop ball” or whatever and see that it’s not spinning in the right direction. The Magnus Effect dictates that air rushing around a spinning ball will go across the sides at different rates, creating a difference in air pressure. When the difference gets to be enough, the ball moves.
So, as shown in the illustration here, if you want the ball to drop sharply, it has to be spinning 12 to 6. No other spin will create that same effect. For a right handed pitcher to throw a curve ball, the ball has to be spinning 3 to 9 (from the pitcher’s perspective), or darned close to that.
So when you’re working with a pitcher, that’s the first thing to check on a movement pitch — the direction of the spin. Because if you don’t have that, none of the rest of it matters. You can do all the other mechanics perfectly, but if you’re not releasing the ball in a way that imparts the proper spin you’re wasting your time.
Keep in mind that a drop ball is not a ball that angles downward. It is a ball that comes in fairly flat, or maybe with a slight downward angle, and then drops suddenly — the old “falling off a table” description. A curve ball has to be more than a pitch that moves from throwing hand side to glove side. It has to be traveling in one direction, then suddenly change directions. If it doesn’t, it’s not a true curve ball.
The speed of the spin is the other factor. Once you have the direction correct, you need to make sure it’s spinning fast enough to move. The faster the spin, the more the ball will move because the bigger the pressure differential will be on the ball. Balls that spin in the right direction, but tumble more than spin, won’t move. You don’t need a lot of forward speed on the pitch to get it to move either. Even a 40-45 mph pitch can move if it’s spinning fast enough.
Once you have the spin direction and spin speed, then it’s time to worry about locating the pitch. Up until that point you’re wasting your time. Focus on good spin and the rest will fall into place. And if you have a pitch that isn’t moving sharply, check the spin. You may have some work to do.