In 2005, Affeldt was again expected to be the Royals' closer. However, he did not get a save opportunity until April 16 against Detroit, and he was unable to finish that game because of a groin injury that landed him on the disabled list again. After rehabbing in Omaha, Affeldt returned to the Royals on June 4. He was no longer the closer, however, because Mike MacDougal had been closing well in his absence. Affeldt was not healthy for long, as he returned to the disabled list on June 20 after reaggravating the groin injury.