My bad I totally misinterpreted what you were saying, when I initially read "shoulder rubbing" I thought of a coach's and player's each individual shoulders rubbing against each other. Seemed like a weird idea that I didn't quite understand. But if you mean shoulder rubbing like a massage type of action then yes I agree with you, unless for injury purposes, shoulder rubbing shouldn't take place. My bad for the misunderstanding.
All good! I didn't express it very clearly either. Just a good example of how people perceive things differently!