1972 would be Duncan's best season offensively as he hit 19 home runs with 59 runs batted in, although his batting average slipped to .218. He committed only five errors in 113 games played for a career-high .993 fielding percentage, second only to Johnny Oates among American League catchers. With Duncan calling the pitches, the Athletics' pitching staff led the league in winning percentage and in shutouts and, once again finished second in earned run average as, the team captured their second consecutive Western Division title. Despite Duncan's production, Athletics manager Dick Williams, a proponent of the platoon system, began using Gene Tenace as the starting catcher during the last month of the season. The Athletics defeated the Detroit Tigers in the 1972 American League Championship Series and then the Cincinnati Reds in the World Series.