Rosario broke out of a 5-for-31 slump Saturday, reaching base five times as the Tulsa Drillers rolled to a 15-3 drubbing of the Northwest Arkansas Naturals.
The 15 runs were a season high for the Rockies' Double-A affiliate, which collected 17 hits and drew 10 walks.
Rosario, MLB.com's preseason No. 41 prospect, recorded his first four-hit game in nearly three years. After striking out against Naturals starter Edgar Osuna (3-1) in the opening inning, he singled in the third and fourth and doubled in the sixth and seventh. He entered the batter's box in the ninth, seeking his second career five-hit game but walked on four pitches.
The native of the Dominican Republic went 5-for-5 with a pair of homers on July 8, 2008 while playing for the Rookie-level Casper Ghosts.
On Saturday, he was still awfully successful. So too was the rest of the Drillers lineup: Eight of nine batters collected at least one hit and the ninth -- No. 9 hitter Warren Schaeffer -- drew three walks and scored twice.
Rosario also formed a strong battery with Juan Nicasio. The 24-year-old right-hander allowed two runs on seven hits while striking out seven over seven innings before handing the game off to Stephen Dodson.
Like Rosario, Nicasio (5-1) signed with the Rockies as a non-drafted free agent out of the Dominican Republic. He's won four straight starts, leads the Texas League with 47 strikeouts in 35 2/3 innings and shares the top spot in victories with Dodson.