The second most common imbalance I see is the external rotators.
I've seen a lot of guys coming into our performance centers, and when we put them on a rotator cuff program, their bench press, their incline press, and their chins all go up just because the external rotators don't inhibit the internal rotators anymore.
One of the primary reasons that athletes, especially bodybuilders, often avoid exercises for the external rotators is that they have to start with embarrassingly light weights. Jim McKenzie is a professional hockey player who went from a 280-pound close-grip bench press to 380 pounds in less than four months.
For the first three months we did no bench pressing. Because his external rotators were so weak, he had to start with five-pound dumbbells when performing many of these exercises! He swallowed his pride, and the results speak for themselves.