McGregor was solid in two postseasons with the Orioles in 1979 and 1983. McGregor sent the Orioles to the World Series by clinching the 1979 ALCS with a Game 4 shutout of the California Angels. He pitched a complete-game victory in Pittsburgh in Game 3 of the World Series. Despite taking the loss in Game 7, McGregor yielded two runs in 8 innings to Willie Stargell and the eventual champion Pirates.