Michael Dennis Armstrong (born March 7, 1954) played Major League Baseball from 1980 to 1987, mainly as a relief pitcher. He played college baseball for the University of Miami.

Armstrong originally was drafted by the Cleveland Indians in the ninth round of the 1972 draft, but did not sign. He was then drafted by the Cincinnati Reds in the first round (24th overall) of the 1974 amateur draft. While still in the minors, Armstrong was traded to the San Diego Padres in 1979. He made appearances in the majors with the Padres in 1980 and 1981, but mainly played in the minor leagues. Prior to the start of the 1982 season, Armstrong was purchased by the Kansas City Royals. There, Armstrong pitched regularly, with over 100 innings in his two years with the team and had an earned run average under 4.00.

Armstrong played in the pine tar game between the Royals and the Yankees on July 24, 1983, earning the victory; a victory it took him almost a month to pick up. "It was wild to go back to New York and play these four outs in a totally empty stadium," Armstrong said. "I'm dressed in the uniform, and nobody's there." He went 10-7 that season in 58 appearances, notching career highs in wins and games.

The 6-foot-3 right-hander was traded to the Yankees after the 1983 season in a deal that brought Steve Balboni to the Royals. While Balboni went on to slug over 100 home runs and contributed to the Royals 1985 World Series triumph, Armstrong reported to spring training in 1984 with a sore arm, limiting him to two Grapefruit League appearances. As a result, Yankees owner George Steinbrenner filed a grievance with Baseball Commissioner Bowie Kuhn. Despite efforts to get another pitcher other than him from the Royals, Armstrong remained with the Yankees, though he spent most of his time with their AAA Columbus farm club from 1984 to 1986. Armstrong finished his Major League career with the Cleveland Indians in 1987.

[ Source: Wikipedia ]