Duffy hasn't pitched in relief since he was just starting out in pro ball in 2007, and he did it just twice for the rookie-level Royals in Surprise. Every regular-season appearance since has been a start.
On Thursday, he made his first relief outing since Yordano Ventura bested him in their duel for the last spot in the Royals' rotation. He pitched a perfect inning with three flyouts.
"It was nice to come in and not really know the amount of time you're going to have to warm up," Duffy said. "I think I was comfortable with it because I wasn't thinking so much. I just went out there with my best stuff against their best stuff. I was really fastball happy, they put the ball in play and I had a quick inning. It was nice, I think I can build on it."
The Royals' internal debate has been over whether it'd be better for Duffy to prepare himself as a starter in Omaha's rotation or face Major League hitters out of KC's bullpen. An important consideration, of course, is would he contribute more to the bullpen than, say, either of the two other lefty candidates, Francisley Bueno and Donnie Joseph?
"I'm just trying not to think about it too much and not worry the whole debate," Duffy said. "Just do what I've got to do and try to take advantage of the opportunity that they've given me out of the 'pen because this is something I've wanted to do for a long time."
Duffy said he approached Royals officials about the bullpen idea.
"It was a mutual thing. We were on the same page. We just came to each other at the same time basically and I just threw it out there," he said. "I really do have confidence that my game will play really well out there, and I'm just excited for my next outing."
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.