Let's say the catcher gives a sign for a slider and sets up on the outside corner of the plate with his glove. The pitcher stares at the glove during the delivery and throws the ball like he always does. Because he is focusing on the glove, the ball has a tendency to leave the hand and proceed straight towards the glove like a fast ball. The slider than breaks low and away into the dirt. Ball one.
Left ear to glove - 2 to 8 and a 12 inch break
(Photo by Steven M. Falk)
Suppose your breaking pitch is a slider that breaks about a foot and also breaks from 2 to 8 (think numbers on a clock). If the catcher sets up with his glove on the outside corner at the knees, think of that as 8 o'clock. 2 o'clock and about a foot away would be approximately the catcher's left ear. The pitcher should set his sights on this location (catcher's left ear) during his delivery. When he releases the ball, the pitcher should want the ball to travel directly towards the catcher's ear. Because of the slider spin applied to the ball, the pitch will then break down to where the glove is located. Strike one.
If a pitcher wants to change the location of the pitch, he can just change his sights instead of trying to change the grip or the spin. Trying to alter those things usually turns out badly. A pitcher who wants to strike out a batter with a two strike slider in the dirt sometimes makes the mistake of thinking he has to snap off a better one by changing his grip or tightening up the rotation. Instead, he should just throw it the same way he always does and just set his sights differently. This time, he may set his sights on the catcher's chin, knee, or glove and have the ball break into the dirt like he wanted with two strikes.
Every pitcher is different in terms of how much his breaking pitch(es) break and in what direction. Each one needs to determine where his sights need to be for each different pitch. From there, moving a breaking ball around the zone just becomes a matter of changing your sights.