For anyone who has a pitcher whose screwball either isn’t breaking enough, or else it’s acting more like a riseball, try this.
Have her enter the release point with her thumb facing forward. This will really help ensure her hand is in the proper position to complete the snap properly by keeping her hand inside the ball at the release point – which simply means she will keep her hand between her body and the ball throughout the release point.
Too many pitchers enter the screwball with their thumbs sideways which really limits the amount of twist and therefore, spin and movement the pitcher can get on the ball.