when i was a kid, 40 starts and 250-300 innings were very common. The flame out rate of pitchers didn't seem much higher than today.
I wonder what would happen if pitchers were asked to pitch a little more. With medical procedures what they are today, there might not
be much of a price to pay physically. Teams with just a few good pitchers might be able to compete, and fewer pitching changes would speed
up the game.