Thanks for the link. This is a very good journal and a very well written article. Dr. Kelly's discussion on kinetic chains gives validation to the importance of correct technique and how dysfunction in one area can affect function in a seemingly unrelated location. His discussion of the affects of posture on shoulder function is right on and reinforces the importance of correcting imbalances of shoulder girdle stabilization.
Dr. Kelly's exercise recommendations are a very good start on rehab for scapular (shoulder blade) instabilities. Eventually the shoulder complex needs to be strengthened for stabilization in all functional ranges of motion. This applies especially to overhead positions in the overhead athlete.
Just a note of clarification: The balance between the scapular retractors/depressors (mid and low traps) and the serratus anterior (a protractor) maintains proper relationship between the scapula and rib cage (controls winging). Actually the serratus ant is a protractor (at least the lower fibers are) that is why the push-up plus is the best exercise for that muscle.