Mickey Lolich, 376.0 innings in 1971
Wilbur Wood, 376.2 innings in 1972.
I was reading Kepner's K: A History of Baseball in Ten Pitches and he had the bit about Wood having the most innings pitched since 1917 and so I looked it up and noticed Lolich's season the year before. So Lolich had the most innings in 54 years and the next year Wood beats him by 2 outs. Baseball is weird.
Baseball reference has the top 500 seasons by IP, which goes down to 330 IP. 473 of them were before 1920. Here are the ones since 1920:
So, 8 in the 20s, none in the 30s, 3 in the 40s, 3 in the 50s (all Robin Roberts), 2 in the 60s, and 11 in the 70s. No one has hit 330 IP since Niekro in 79. So what happened in the 70s to reverse a decades long trend and then why did it stop again?
I guess 8 of the 11 were Wood and Niekro throwing knuckleballs and Perry throwing KY balls but it's still weird. Candiotti topped out at 252 and Wakefield and Dickey never got close to 250 throwing knucklers.