Look at today I believe Arroyo led all pitchers with something like 240IP. Koufax threw 323 about a 1/3 more. It's no wonder he had a dead arm. Not showing my age but I kind of remember that diagnosis at the time. You didn't come out of a game in those days because the closer was some washed up guy who couldn't start anymore so they put him in the bullpen. And even a tired Koufax was 100x better than that.
Back to the original idea though, today's pitchers do seem to get hurt more and they are all on pitch counts. Has anyone ever heard Tommy Lasorda talk about pitch counts? Should we let pitchers use their natural motions and not try and put them in a cookie cutter? I know my sons high school team wants every pitcher to start their motion with a step to the side not back. They all need to be able to pitch the whole game or they won't use them.