Bill, sorry no one has answered your question. I think it is probably because it is so hard for us to say with or without more information. None of us here are orthopedic professionals and even if we were, it would be irresponsible to answer without direct contact with your son. I will say that shoulder problems are much harder to diagnose and fix than elbow problems. At least from what I have read. I have also read some stuff lately that shows that the chance of coming back from a shoulder injury is much higher when surgery is not involved than when surgery is involved.
I don't know much about recovery time from this sort of injury, but I would make sure he is going to a very good orthopedic doctor who knows how to deal with baseball players. If you go to the following website, you can ask there if your current doctor has the kind of qualifications you are wanting and you can get a referral to a good doctor near where you live that can help your son, especially if you need a 2nd opinion, or your doctor is not trained properly in this area.
http://asmiforum.proboards.com/index.cgi?
I wish the best to your son. Let us know how things turn out.