Chen, taking over in the fourth inning, had three perfect innings with a strikeout in each. He threw 36 pitches, including 25 strikes, in his second Cactus League outing.
"The results are there, I feel like I'm making good pitches, keeping the ball down, changing speeds really well," Chen said.
There's still some work to do, though, on his velocity.
"That's the one thing I wish I had a little more," Chen said. "I saw a couple times it was 82, 83 [mph]. I think I hit 85 one time, but I'm hoping as Spring Training progresses, I'll get stronger and stronger, and I'll be able to reach back and get some velocity whenever I need to."
Chen is already in the rotation as the fourth starter, but Duffy is trying to win the fifth spot over several other aspirants. In his first outing, Duffy gave up two runs in two innings including a home run to the Rangers' Prince Fielder.
This time, Duffy was tagged for four runs, three on back-to-back homers by Ryan Ludwick and Todd Frazier, in the first inning. Then, he pitched a perfect second inning although by then his pitch count had reached 40 and the Royals didn't send him out for a scheduled third inning.
"In the first inning, he was just off a little bit and some of those pitches probably could've been called strikes, but where he got hurt were pitches up the zone," manager Ned Yost said. "The second inning, man, he was great."
Duffy was pleased with his stuff and, except for an elevated pitch to Ludwick, with his location.
"I feel like 99.95 percent of the time if I throw the way I did today, I'm putting up two zeros and probably three," Duffy said. "I felt like I threw the ball very well, located very well."
"If that's how I've got to get outs, I guess I'll take 'em that way," Duffy said.
Overall, Duffy thought he pitched pretty well.
"I'm really pushing to make that squad and I've got to get out there and do what I did today," he said. "Just hopefully next time there'll be better results."
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.