Cuellar had a 24-8 record in 1970, when he led A.L. pitchers in victories, complete games (21) and winning percentage (.750) and pitched the Orioles to a World Series championship with a Game 5 victory against the Cincinnati Reds.
It’s that bolded part that caught my eye. Nowadays, that’s unheard of. Wikipedia says the last pitcher to pitch 20 complete games in a season was Fernando Valenzuela in 1986. Of course, it’s nowhere near the top-100 list for complete games in a single season, but the latest season on that list is 1892 and to break into it, you’d have to pitch 51 games in a single season.