I definitely second that vote.
I believe Cosgrove, Cressey, and Robertson have all used a similar analogy; that if a baseball player came to them, the first thing they would do is train the opposing muscles, and the absolute last thing they would do is train the movement against resistance. Unless your league is using a 6-pound softball, there's no point in using the band that way.
Use the weight room for building a stronger/faster body, then use time on the field to translate that strength/speed for the game.
Just as important as the rotator/shoulder area is the hips, abs (core), and grip. A weak point in any of those, and it doesn't matter if your shoulder is super-healthy.
I'd consider going on a primarily dumbbell routine for a few weeks, with limited barbell exercises, in conjunction with a basic rotator cuff pre-hab program. Big exercises like DB snatches, the clean and press, pull-ups (especially to the sternum, if possible), bent 2-DB rows, and full contact twists (requires a barbell, but it's awesome anyway), will be key players.
Kuz, are you looking to improve your arm for pitching, or for making those big bomb tosses from deep, deep right field?