As a Cardinal in , he threw his only MLB complete game and shutout on May 27 at Busch Memorial Stadium, allowing only two hits to the Chicago Cubs and striking out three, with no walks. His season was also notable. Called up by the Tigers from Triple-A Toledo in May, Zachary became a reliable member of manager Billy Martin's bullpen, compiling a sparkling 1.41 ERA with one win and one save in 38 innings pitched as Detroit captured the AL East title. Zachary then made his only postseason appearance in Game 2 of the 1972 American League Championship Series against the Athletics at the Oakland Coliseum. Entering the game in the fifth inning in relief of Woody Fryman with Detroit trailing 1–0, Zachary had severe control issues. He threw two wild pitches, allowing an insurance run to score from third base, and walked Joe Rudi. He left the game without recording an out, and was charged with one earned run in Oakland's 5–0 victory.