During 1965 spring training, the Orioles figured out that McNally's body language was giving away to the hitters which pitch he was going to throw in an at bat. He worked on the problem and had it corrected before the season started. Though he made a few relief appearances throughout the year, he was mainly used as the team's fifth starter. Through the end of May, he had a 4.19 ERA, but he pitched better in the succeeding months. He quit smoking midseason and gained about twenty pounds, which he credited to his improvement, though after the season he would resume smoking again. In the second game of a doubleheader on August 4, he threw a shutout as the Orioles defeated the Angels 8–0. For the second year in a row, he threw a shutout on October 1, limiting Cleveland to two hits in a 2–0 victory in the first game of a doubleheader. McNally topped the 10-win mark for the first time in his career, finishing the season with an 11–6 record. In 35 games (29 starts), he had a 2.85 ERA, 116 strikeouts, 73 walks, and 163 hits allowed in innings.