say the plate is money , protect it.

Sounds like way to much movement, every time the head moves the ball moves visually, straighting up changes the plane of the bat (high swing), but I don't understand how he can open up and close at the same time and get his lead foot planted. Can you explain.

Oh I see now...try making him swing off the tee standing back in the batters box toward 3rd base in slow motion forcing his arms to fully extend. Speed up the swing little by little until he can swing 100% correctly. Then go to soft toss for about 10 minutes, if he looks good, then try pitching back at the mound. If he starts pulling out again, go back to the tee.
Good Luck, Coach!

have him line up as if he were going to swing,and put a tee on the outside corner of the plate and have him swing,but make sure he doesnt change his stance because of where the tee is
good luck!