The Rockies broke a scoreless tie in the seventh when Chris Nelson drew a leadoff walk from Dale Thayer (0-1).
After Yorvit Torrealba sacrificed Nelson to second, Helton came to bat for De La Rosa and golfed a 2-1 pitch over the right field wall for two runs.
De La Rosa (1-1) scattered two hits and four walks over six scoreless frames, while fanning four.
Jedd Gyorko supplied the only RBI for San Diego.
Beyonce flaunts bikini body, Blue Ivy in vacation pics
Benedict Cumberbatch's dramatic reading of R. Kelly lyrics is just what you need