Rob, If the ball is low and the bat high you will start your swing down but the body tilts and changes the orbit to a slight uppercut.
Swing down is an old cue to stop kids from dropping the hands IMO
I think if I had to start all over I would examine ways to get a circular hand path. The human tendency is to swing straight at whats coming. The knob should be going to 2B at launch for a RH kid.
Turning hips only link properly with turning hands