Rosario, who was called up from Triple-A New Orleans on Friday, made just his seventh career appearance, and his first since Sept. 25 against the Brewers. The 26-year-old right-hander entered the game with one out and runners on the corners in the seventh and proceeded to pitch 1 2/3 hitless innings of relief.
"Rosario did a tremendous job," Guillen said. "Great job by him."
Rosario induced an inning-ending double play against the first batter he faced, and then got through the eighth, allowing only one runner to reach -- on an error by Omar Infante. He capped off his outing by striking out Desmond Jennings.
What Guillen was most impressed with about Rosario, however, was his velocity. The righty touched 97 mph on the radar gun and his fastball consistently hit 95-96 mph.
"I didn't know this kid would throw that hard. I kind of liked it," Guillen said. "He throws hard, he's got good stuff and he throws strikes. You throw that good, you throw strikes, you're going to be in a good position to repeat."Rosario struggled in his second appearance, allowing three runs on four hits without retiring a batter in the eighth inning of Saturday's 13-4 loss.