Righetti made his major league debut with the Yankees on September 16, 1979, wearing uniform number 56. In this game against the Detroit Tigers he pitched five innings, striking out three and allowing three hits, six walks, and three earned runs. After Righetti made his second start, Yankees' manager Billy Martin declared that Righetti "will win 20 games next season". However, Righetti struggled with his control, and spent the 1980 season with the Columbus Clippers of the Class AAA International League, where he had a 6–10 win-loss record and a 4.63 ERA with 101 walks and 139 strikeouts in 142 innings.