> Is "the fence drill" the only known way to teach keeping hands inside the ball?
Best drill is to set up on tee, choke up 3-4 inches on bat, and hit with hands outside the ball. Caution: wear a cup. If player still can't hit with hands outside the ball, move to live pitching and try same. After several "hits" players learn to keep their hands inside the ball.
Seriously though, its hard to have a circular hand path when doing fence drill, ie Epstein. It can be done but tendancy is to straighten out handpath from lag position. Other problem with fence drill can be too much BHT with bat handle being pulled way too far back.