Matzek has struggled with his control early in the season, particularly in his latest start Wednesday against Arizona. He pitched two innings and gave up four runs, three hits and six walks. Manager Walt Weiss said the Rockies were still considering their options for Matzek's replacement in the rotation.
Matzek is 2-1 with a 5.96 ERA in five starts for the Rockies this season, his second in the big leagues. He is 8-12 with a 4.06 ERA in 24 career starts.
Rosario played in 10 games for the Rockies before being optioned two weeks ago to Albuquerque, where he hit .343 with four doubles and four RBIs in nine games. He has three doubles and a home run in 14 at-bats for the Rockies this season.