Stallard appeared in four games in his debut season of
1960. He faced 15 batters without giving up a single hit, and amassed 6 strikeouts. Three of his appearances were against the New York Yankees. Stallard's first victory came on August 10, striking out eight in 8 innings pitched in a 3–2 victory over the
Minnesota Twins. Stallard started in 14 of his last 15 appearances for the season going 2–7 with a 5.00 ERA and 69 strikeouts in 86 innings pitched as a starter.
Roger Maris's 61st home run On October 1, 1961, New York Yankees
outfielder Roger Maris hit his 61st home run of the season off Stallard, breaking
Babe Ruth's single season record of 60. The contest between the Red Sox and the Yankees was the final game of the season. Stallard, then 2–6, faced off against Yankees right-hander
Bill Stafford (12–9). In the first duel between Maris and Stallard in the first inning, Stallard threw a changeup to Maris that ended up being a soft fly to left field. In the fourth inning, Stallard fell behind 2–0 to Maris. Up to that point, Stallard had said that he was probably having the best game he had ever pitched. Stallard threw a fastball, and Maris hit it over the wall for his 61st home run. It was Maris's only hit off Stallard in seven lifetime at bats. Stallard felt no shame over the ordeal, saying, "I'm glad he did it off me. Otherwise, I would never have been thought of again. That was about all I did, and I've had a good time with it." There has been speculation that Stallard grooved the pitch in an attempt to help Maris hit the home run, claims which he denied. Stallard struck out five and gave up five hits and just the one earned run in seven innings on the outing, but the Red Sox failed to score in a 1–0 loss, dropping him to a final record of 2–7 for the season. Stallard appeared in only one game for the Red Sox in
1962, spending the rest of the season with the minor league Class AAA
Seattle Rainiers, where he threw for a 7–6 record and a 3.49 ERA. ==New York Mets==