One of the keys to a pitcher’s delivery is what coaches call “separation.” This is the point when your hands separate from one another, taking the ball from the glove and into your bare hand.
The rhythm of the delivery is affected by when and how you separate. This separation should happen near the center of the body, which will help to keep the delivery in sync.
In addition, you want your throwing arm and lower body to work together. As you separate your hands, the ball will come back in the throwing hand while your stride foot goes forward towards the plate. The length of the arm swing and the length of the stride will affect the timing of this motion. You need to work on this in the bullpen so that your delivery is rhythmic and smooth.
One of the drills you can do for this is a rhythm drill where you start from the stretch position. As you reach your gathering point to separate and stride, you should land with you stride foot and pause. You will then push off of the stride foot to move backwards into your gathering point, bringing your hands back together. From there, you will separate and stride again. You will pause once more on your stride foot with your throwing arm back, before pushing off your foot to move back into your gathering point.
Finally, you will separate and stride again, completing your delivery and throwing the pitch. This gives the player a balanced feel for where the separation should take place. This drill emphasizes how the stride leg and throwing arm work together. If you do this in the bullpen over and over again, your delivery will start to get more consistent, rhythmic and fluid, which usually leads to more strikes.