>>> Have him hit the center of the baseball or the inside of the baseball as opposed to the outside of the ball. You shouldn't be casting your arms if you are hitting the center to inside of the ball. My guess is he is pulling the ball and the only way to pull the ball is to hit the outside of the ball. Have him work on hitting all balls right up the middle. The tee is the best place to correct this. <<<
Although I have no problem with batters pulling the ball, I agree with you that they should practice hitting the ball straight-away. I also agree that "casting" can be a problem in the context you used the term. However, I would like to take this opportunity point out to the readers that I feel linear thinking has given the term "Casting" a bum rap.
The post below from the Archives explains my reasoning and I would appreciate your thoughts.