Fixing arm circle issues is by far one of the hardest things to fix. Coach Barb Sherwood provides an arm circle drill to help correct this, but she does note it is not only hard to fix... but takes a long time to fix as well. Utilize this wall drill to help your pitchers work on their arm circle mechanics.
How it works: A pitcher stands facing a wall with her throwing arm a few inches away from it. About 40 feet away, a catcher stands ready for the pitch. With ball in hand, the pitcher circles her arm along the wall as she executes the pitch. The catcher receives the ball, then returns it to the pitcher so the drill can repeat. Allow the pitcher to begin slowly, then encourage her to pick up her speed as she gains confidence.