Herrera was claimed off waivers by the Royals on Saturday.
He was designated for assignment by the Reds, and the Royals decided he was worthy of a spot on their 40-man roster. Herrera goes from an organization with a lot of outfield depth to one with very little outfield depth, so this is a good move for him. He is hitting .267/.320/.500 with three home runs and two steals in 98 Triple-A plate appearances this season.