https://www.baseball-reference.com/players/g/galvipu01.shtml
Pud Galvin in 1884 had a WAR over 20, with a 42-22 record and 636 inings pitched with a 1.99 ERA
Thats like 3 seasons of pitching nowadays
And 20 WAR, for perspective, Barry Bonds and Babe Ruth's absolute best seasons were like 11-12 WAR