Duffy was back off the disabled list (biceps tendinitis) and offered 4 2/3 serviceable innings in the Royals' 8-2 triumph over the Mariners on Wednesday.
Duffy came in with a pitch limit of 90 and he reached 88 pitches when the Mariners started to mount a slight rally in the fifth. That's when manager Ned Yost came and got him.
"I really wanted him to get that third out in the fifth and get the win," Yost said. "But I couldn't jeopardize the win.
"He was getting fatigued and that was affecting his command. But he really pitched well, I thought."
Duffy agreed with the hook.
"I just kind of emptied my tank that inning," he said. "I'm just glad I could help us get a win."
Duffy gave up eight hits but walked none, a noticeable measurement of success for him. He gave up one earned run.
"Yeah, the no walks, that's a good starting point," Duffy said. "Got my pitch count up a little too fast but overall it all felt pretty good."
Duffy had been eager to try out his new windup -- he used to start with his hand belt high but now lifts his hands and arms over his head.
"It felt really comfortable," he said. "I'm just able to stay over the rubber longer. I'm not missing so much arm side and glove side. This was a good first step."
Jeffrey Flanagan is a reporter for MLB.com. Follow him on Twitter at @FlannyMLB. This story was not subject to the approval of Major League Baseball or its clubs.