The Yankees reached the World Series, facing the Pittsburgh Pirates. Pennock pitched a complete game against the Pirates in game three of the 1927 World Series, not allowing a hit until the eighth inning. Pennock's performance drew praise from teammate Babe Ruth. The Yankees swept the series from Pittsburgh. After pitching a three-hit shutout against the Red Sox on August 12, 1928, he missed the remainder of the season, including the 1928 World Series, with an arm injury. His five shutouts and 0.085 home runs per nine innings pitched led the AL. His 2.56 ERA trailed only Garland Braxton, while his 17 wins tied for eighth place. Though the Yankees defeated the Cardinals in the 1928 World Series, the Yankees' starting rotation without Pennock was likened to "a three-stringed ukulele."