A surprise 1985 Opening Day starter at second base, Duncan took over at shortstop and placed third in the NL Rookie of the Year voting. But some criticism apparently shook his confidence and his batting average plummeted, leading to a demotion in 1987. He returned as a utility man in 1989 and went to the Reds in the Kal Daniels trade.
Duncan was the Reds’ primary second baseman (and led the league with 11 triples) when Cincinnati won it all in 1990, but was shipped to Philadelphia after splitting time with Bill Doran in 1991. Duncan started regularly at a variety of positions for the last-place Phillies, turning up most frequently in left field and as a backup to Mickey Morandini at second base.
As the Phillies surged to a pennant in 1993, Duncan’s everyday playing time ebbed, but he still served as a valuable reserve behind Morandini and shortstop Kevin Stocker. In ’94 he shifted to third when Dave Hollins fell victim to injuries, but was elected to the All-Star team at second base (thus replacing perennial NL starter Ryne Sandberg, who had retired before the season.) It was the only All-Star appearance for Duncan, who remained typecast as a utilityman and was traded back to the Reds in August 1995.
Duncan signed on with the Yankees as their everyday second sacker in 1996 and batted .340 for the World Series champs. But after losing his regular job in ’97, Duncan mouthed off to owner George Steinbrenner and was dealt to Toronto in July. Unable to replace the slumping Carlos Garcia, he spent the next season in Japan. “I should’ve kept my mouth shut when I was with the Yankees,” Duncan told Bob Klapisch of the Bergen Record in 1999. “In the big leagues, you take everything for granted.”