He had thrown in the bullpen earlier on Sunday afternoon. Herrera also had a throwing session during Saturday's workout that went well.
Herrera developed a tight right forearm while walking the only batter he faced in Game 1 of the ALDS on Thursday night. He was taken out immediately and wasn't available for Game 2 on Friday.
The hard-throwing right-hander has developed into the Royals' seventh-inning specialist, setting the table for Wade Davis in the eighth and Greg Holland in the ninth.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.