The Orioles won the AL East for the third straight year in 1971 and faced the Oakland Athletics in the ALCS. Used as the Game 1 starter, McNally gave up three runs over seven innings, saying after the game he did not have his best stuff. However, Baltimore scored four runs in the seventh inning to rally from a 3–1 deficit, giving McNally the win in a 5–3 victory. After sweeping Oakland, the Orioles faced the Pittsburgh Pirates in the 1971 World Series. McNally again started Game 1, prompting Pirates' manager Danny Murtaugh to bench Richie Hebner and Al Oliver (left-handed batters) in favor of Jose Pagan and Gene Clines (less productive right-handed batters). In the second inning, errors by Mark Belanger and Elrod Hendricks led to three unearned runs scoring for Pittsburgh. However, McNally would not allow any other runs, limiting Pittsburgh to three hits and retiring 19 straight hitters at one point in a complete game, 5–3 victory for Baltimore. He was less effective in Game 5, allowing four runs (three earned) in four innings as the Orioles lost 4–0. In Game 6, with the score tied 2–2 and two outs in the 10th inning, he entered the game, walked Willie Stargell to load the bases, then retired Oliver on a fly ball to keep the game tied. Brooks Robinson hit a sacrifice fly in the bottom of the inning; McNally earned the win as the Orioles prevailed 3–2. He was brought in to face Stargell with two runners on base in Game 7, but McNally got Stargell to ground out to end the inning; however, the Orioles lost that game 2–1, as the Pirates won the series in seven games.