In his rookie season, Duncan led Raiffesen Dornbirn Lions to the Austrian Division II Basketball League championship. Averaging 25.5 points in the semifinals, he was named Finals Most Valuable Player and most notably recorded a game-winning shot in the Final Four round.[3]
On August 7, 2015, Duncan signed a one-year deal with Apollon Patras of the Greek Basket League.[5] He left Apollon after appearing in seven games. On December 2, 2015, he signed with KTP Basket Kotka for the rest of the season.[6]
On November 21, 2016, Duncan re-signed with Windsor Express.[7]