[1] For 1979, he was promoted to the Double-A West Haven Yankees of the Eastern League, where he went 10–6 with a 3.81 ERA and 113 strikeouts in 144 innings of work.

[2] He was named to the postseason All-Star team and won the Southern League Most Outstanding Pitcher Award.

[3][4] In 1981 with the Triple-A Columbus Clippers in the International League, he went 8–6 with a 3.23 ERA and 57 strikeouts in 103 innings before being called up to the Yankees after the season.

[1] McGaffigan made his major league debut on September 22, 1981, pitching three innings of relief against the Cleveland Indians at Yankee Stadium.

[1] Prior to the 1982 season, the Yankees shipped him to the San Francisco Giants in a trade for Doyle Alexander.