Bouton's talk of pain and the relationship of a pitcher and his arm (both from personal experience and that of his teammates) pretty much mirrors what Ojeda said

Oh, and of course I left out the most relevant section:

I told Steve that I took eight aspirin a day but that sometimes I needed a little more help. Anti-inflammatories, stuff like that. I started the season in the bullpen and got my first start April 22. Our routine was that after every start, I sunk my elbow in a bucket of ice (doubled as a beer cooler) for 20 to 30 minutes. A few cigarettes and beers later, no pain. Imagine. Not much other than that.

By then, my love affair with my changeup was in full bloom. Quite simply, it hurt less to throw. By June, we were eight or nine games up, and it was over for the rest of the N.L. East. But I had a problem: my elbow was flat-out quitting on me. Time to get in the jar. The team doctor examined me and said I needed to rest it. That wasn’t going to happen, I told him. I played the “this conversation never happened” card, and he respected my decision to take responsibility for the consequences. He prescribed the pills I needed.

Throwing overhand is an unnatural motion, meaning, we're not built to throw overhand. It kills the shoulder, over time. The arm is meant to throw underhanded. That arc is our natural motion. "King of the Hill" Eddie Feigner pitched until he was 75. He was unhittable for most of his life.