Medical professionals who have completeled their residency and specialize in orthopedics have stated this was the right move. Why am I to believe your brother, a surgical resident, over the specialist? Also, it's very comical that you ridicule someone for using the opinions of others while doing the same. Stop being so hypocritical. If their opinions means nothing, then so does your brother's. Besides, the people I believe are right are certainly more credible and have superior training to your brother.
The analogy fits. The muscles of the shoulder help hold the joint together, and the lack of regular rest combined with more intense action for a reliever put more strain on those muscles. This is about stress on the muscle. When the muscle is overtaxed, it will fail, for the sprinter, or fail to do its job, for the reliever. Anyone with even minimal understanding of muscle physiology knows that a muscle is more likely to fail after repeated intense use than it is to fail after regemented and less intense use.
The problem here is you are too full of yourself to drop your preconceived notions. I, like you, originally thought relieving was a better way to avoid injury, and it probably still is for most injury concerns, but this one is different. However, I know what I know and what I don't. You define idiocy by sticking to your guns in the face of contrary expert analysis. Oh, I questioned the opinion at first, but the reasoning was cold hard common sense regarding the physiology. So, I accepted that my perceived notion was wrong and moved on. You can't do that because your ego won't allow it. Pity for you.