Duncan was in his first year with the Rays, having made the Opening Day roster out of Spring Training. He previously played in parts of three seasons each for the Yankees and Indians and has posted a .226 average with 43 homers and 144 RBIs in 330 games through 2013.
Duncan's move off the Major League roster made room for Luke Scott's return from the disabled list after missing the first 29 days of the season with a right calf strain.
Owen Perkins is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.