Duncan was batting .309 with six homers and 17 RBIs in 15 games for Scranton/Wilkes-Barre. In three games against Cleveland's Triple-A affiliate this week, Duncan hit two homers and drove in seven runs. Last season, he batted .257 in 34 games for the Yankees.
This is Duncan's second stint with New York this season. He went 1-for-5 in two games before being optioned on April 9.
With the Indians starting left-hander Jeremy Sowers on Saturday and lefties C.C. Sabathia and Aaron Laffey the next two days, manager Joe Girardi needed another right-handed hitter and went with the enthusiastic Duncan.
"We like the energy Shelley brings to the club," Girardi said. "It's good to see him back. He has the ability to bring a spark. We're a high-energy team anyway, but he brings more. He's like one of those little kids you let run around outside so that you can get him to sleep later."
A converted starter, Traber made 11 relief appearances and had a 4.50 ERA.
"It's a new role for Billy [in the bullpen] and he needs to get a little better control of his breaking ball against lefties," Girardi said. "I'll encourage them [at Scranton] to use him against a ton of lefties. Billy knows what we want. He's a bright kid."