Nuno, who missed time with the Orioles earlier this month because he pitched for Team Mexico in the World Baseball Classic, stepped in and allowed three runs on four hits in 1 2-3 innings. The Orioles lost, 7-4.
"We knew that Miley was kind of ill the last couple of days. He said that he couldn't go, and I was the next one in line to get the ball," Nuno said.
Upon his return from the Classic, Nuno gave up a run on two hits last Friday at Pittsburgh.
"The last two outings have been a little difficult for me. I'm not getting those two strikes where I want them to be. It cost me a little bit [Monday]," Nuno said.
Nuno, who was acquired from the Los Angeles Dodgers for Minor League pitcher Ryan Moseley on Feb. 19, said that he feels a little behind because of the World Baseball Classic experience.
"A little transition, being in Arizona and traveling and coming back, the time difference," Nuno said. "Now, I'm getting accustomed to the time change and getting acclimated."
Nuno thinks he knows what's gone wrong for him.
"I'm trying to do too much with two strikes, trying to overthrow. That's not how I've been throwing the past year. [Spring Training in] Florida is different compared to Arizona, the humidity. The ball doesn't spin the same," Nuno said.
Rich Dubroff is a contributor to MLB.com and covered the Orioles on Monday. This story was not subject to the approval of Major League Baseball or its clubs.