Oh yes, when it comes to hitting Bell is only good for beginners. If they want to learn advanced hitting they need to go to Gary Slinger. Slinger can really excells at the type of hip rotation and elbow slotting that prevents Bat Lag.
He is also very good at teaching Bat Drag in loading the wrists to get better bat speed.

This is funny!
Yea I heard the same thing about Bell. He is only good for beginners that's pretty much all he works with. AND>>> Oh no...he does teach
bat lag(NOT TO BE CONFUSED WITH BAT DRAG)

That big dummy says bat lag is normal and somewhat necessary in the swing. As the core+shoulders begins to rotate, the bat drops down into a lag position. As the rotation of the shoulders decrease, the bat then causes it to whip out and into the path of the ball. - This is defined as lag.
I tried telling him that he is full of crap, but he doesn't listen.

So I would give up on him if I were you.
But, you keep going to the ones that teach advanced hitting. I personally have not seen any advanced hitters come through this area with the exception of maybe Alexia Clay. Just because they go to college and play, are they necessarilly advanced hitters.

HEY EVERYONE-There's someone that teaches bat drag you may want to get into! BTW Are you sure Slinger knows you're advertising for him?