 In 2006, he hit 19 home runs for Trenton in 351 at bats, and was twice the league's player of the week.In 2007, Duncan was a member of the International League All-Star Team, and was the Topps IL Player of the Month in May while playing for the Triple-A Scranton/Wilkes-Barre Yankees.While with the Yankees AAA team, Duncan had 25 home runs, second in the International League at the time he was called up, and hit .296 with a .577 slugging percentage in 336 at bats.