When looking at the old timers, I think you have to also work under the assumption that many of them were, indeed, injured and simply played through it as long as they could. Since we didn't have radar, it's hard to tell how much velocity was lost, but I think it is logical to assume that ucl tears happened back then. It's entirely possible to pitch effectively with a torn ucl. Most of the care back then didn't deal with fixing the problem. The major focus was on pain management.