"I have what I have," Duffy said then. "It's something that is inflaming something in there. So we'll get it looked at when we need to. But until then, right now, I could go. Nothing in my elbow is going to compromise my ligament."
Duffy also said he felt a little bit of inflammation last offseason, but thought he could pitch through the discomfort this season.
"I have a high pain threshold," Duffy said.
Duffy didn't start feeling any noticeable pain until August. He eventually was diagnosed with a low-grade pronator strain and was placed on the disabled list.
"A lot of players have slight tears or chips or whatever and play through it," Yost said. "You don't address it until you have to, until it affects your performance."
Duffy said he should be fine for Spring Training after the procedure.
Jeffrey Flanagan has covered the Royals since 1991, and for MLB.com since 2015. Follow him on Twitter @FlannyMLB. This story was not subject to the approval of Major League Baseball or its clubs.