To make room for Eibner, the Royals shipped outfielder Reymond Fuentes back to Omaha.
Fuentes made an error on Wednesday night in a 9-4 win over Cleveland. Royals manager Ned Yost stressed that Fuentes needs to work on his defense at Triple-A.
"It's tough," Yost said. "You know when Alex Gordon and Paulo [Orlando] came up, they had to adjust to the third deck and the energy that's in the stadium. You have to adjust. It's difficult. Paulo kept getting better. It took Gordy a little adjustment time when he first got here, but he got better and better.