""I feel great. I'm exhausted, but I'll continue to bounce back and maintain the way I'm supposed to," Duffy said. "Maybe next time out, I'll go deeper in the game."
In his first action last Monday, Duffy threw three shutout innings for Northwest Arkansas, giving up two hits and two walks with four strikeouts on 63 pitches.
"I think I could do better with putting people away," he said on Friday. "I got five guys on 0-2 today and four of them got hits. If I could get that curveball bouncing on 0-2 instead of throwing a fastball in the zone or a fastball up and in, that'd probably be ideal. You always need to have something to work on."
Duffy went 2-2 with a 3.90 ERA in six starts for the Royals last season before he sustained a left elbow injury on May 13, 2012. The southpaw missed the rest of the season following Tommy John surgery on June 13.
Master Tesfatsion is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.