A first-round draft pick of the Reds in June 1987, Armstrong spent his first two seasons in the majors shuttling between Cincinnati and Triple-A Nashville, where he pitched a 4-0 no-hitter on August 7, 1988. Armstrong didn’t earn a regular spot in the Reds’ rotation until 1990, when he turned in an 11-3 record and 2.28 ERA in the first half and was named the NL starter in the All-Star Game at Wrigley Field. But as the Reds charged towards the World Championship, the promising right-hander went 1-6 with a 5.96 ERA in the second half of the season. He never recaptured the magic of his brief stay in the spotlight.
Armstrong spent another disappointing season in Cincinnati before the Reds dealt him to Cleveland as part of a deal for Greg Swindell in November 1991. By this point, Armstrong had developed a reputation as a pitcher who “thought too much” on the mound, especially with runners on base. The Indians cautiously tried to rebuild Armstrong’s confidence by using him as their fifth starter, but he was moved to the bullpen after losing 13 of his first 15 decisions.
Armstrong enjoyed some success as a reliever, but he returned to a starting role when he was selected by the Florida Marlins in the 1992 expansion draft and suffered through a 17-loss season in South Florida. He caught on in Texas in 1994, and made two good starts for the Rangers before a rotator cuff tear ended in career in April.