Additional thoughts for you and other parents of young pitchers:
”After fall baseball had finished up at the end of November, he had "rested" his arm, other than going to Power Throwing at a local pitching/baseball training center twice a week”
- So, in reality, there was zero rest! HS, summer travel and fall ball through November is longer than a MLB grown man goes through. Then he does Power Throwing right after. Where's the rest? Something for you and your son to commit to going forward: #NoThrowNovember
”hadn't thrown at all over Christmas break. Three weeks ago, he went to the training center and while throwing weighted baseball”
- The only break he took was followed up with a weighted ball program. Was there any easing into this program, with regular throwing, given a little time off? Christmas break plus 3 weeks is pretty much today, so my guess is probably not.
Not trying to make you feel bad, but it seems there were some bad decisions starting this off season. Do not make it worse by having him pitch g through fatigue, injury, etc. It will only end up badly.