The answer is "arm swings".
Dynamic stretching for baseball is the best method to appropriately warm up the muscles, joints, and tendons preceding tossing or strenuous exercise. The old design technique for static stretching for pitchers has ended up being incapable as a warm up, and may even lessen touchiness in competitors.
Arm Swings while standing straight up, you will then swing one arm up over your head with a controlled movement. At that point rehash with the other arm. Perform ten reiterations on each arm. This will enable warm-to up the rotator cuff and upper back.