"I just started feeling discomfort all the time. I couldn't bounce back. It wouldn't get better. Early on in rehab it felt fine. But when the volume [of pitches] started up ... I couldn't keep up with the volume."
After a rocky start in which Medlen made six appearances (7.77 ERA), he was put on the disabled list in May with rotator cuff inflammation.
Medlen, 30, did not see the Majors again after a series of startups and shutdowns during injury-rehab stints. He was finally shut down for the season last month.
And so now Medlen's future seemingly is in question. He twice has undergone Tommy John surgery.
Medlen signed a two-year, $8.5 million contract with the Royals two years ago. There is a mutual option for 2017, but the club has not exercised any mutual options, and the likelihood is high it will buy that option out for $1 million.
Yet Medlen, who was 6-2 with a 4.01 ERA in 2015, is insistent he will stick with baseball and wants to return to the Royals.
"Absolutely," Medlen said. "I am completely interested in still playing. I have a mutual option, but I'm assuming it won't get picked up. I'd love to come back with the Royals. I feel like I'm not done yet with this team. I feel like I owe them something.
"It's a great place to play. I just wish I could have helped more."
Medlen admits there was a point this summer when he wondered if it was worth it all.
"I think at one point, I got a good talking to from friends and stuff," he said. "I got in the dumps. But I want to keep playing and trying. It's too unique of a job to hang it up. You think of the [tiny] percentages of people who get to do this. I'm not done at all."
Medlen said his MRIs this season -- he's had three -- show no damage to his elbow or his rotator cuff. He simply needs to strengthen his muscles around the cuff.
"It's just strength and fatigue issues," Medlen said. "It should be fine [next year]."
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.