Dropping the back shoulder

I can't tell you this applies to you but it could be that your letting your front shoulder fly open before your hands. That is what my son was doing. It looked like he dropped his back shoulder because of this.

Try taking practice swings and some tee work using only your front hand (choke up a bit) - wrap your back hand across your belt. Hope it helps.

baseballislife, Its hard to give advice without a video clip of your swing. But dropping the back shoulder would mean that you would have to colapse the backside leg or over bend it to much. Also dropping the back shoulder could be a result of turning the backfoot.

the back foot turning in the swing isn't like "squashing the bug" the back foot turning is a RESULT of the hip rotation. In other words the hip makes the foot turn (so to speak) not the foot makes the hip turn.
I would suggest that you need to learn what a quick swing is and how to perform it. Not really a drill that you need but some proper instruction is.

The back shoulder will be below the front shoulder at contact. The problem is that the backside collapses. If you lock up your hip rotation, you can dip and your back shoulder collapse.

Jeff Kent is a great hitter to watch -- stays tall and strong and lets the barrel feed. Many hitters collapse trying to swing level going down to the ball instead of letting the barrel feed.

Try to (1) think tall and strong, (2) let the barrel feed, (2) don't lock up or restrict the rotation.