Good hitters drop the back shoulder.
Poor hitters drop the back shoulder.

What is the difference?

Good hitters' drop DRIVES their swing.
Poor hitters' drop then swing.

Good hitters' barrel speed is DURING THE DROP.
Poor hitters' barrel speed is AFTER THE DROP.

Good hitters drive DOWN to the ball....upon which their barrel turns up.
Poor hitters drop then drive UP THROUGH the ball.

In shorthand....it's called corner versus no corner.

Tell 'em where you got it.