 On January 24, 2014, he signed a minor league deal with the Arizona Diamondbacks.Duncan signed a minor league deal with the Cincinnati Reds in May 2014.Duncan was released by the Reds on June 18, 2014

On January 7, 2015, Duncan was announced as the new Manager for the Arizona Diamondbacks Short Season-A Affiliate, Hillsboro Hops of the Northwest League.