De La Rosa walked three and struck out seven as Colorado salvaged one win in the three-game series at Busch Stadium.
Troy Tulowitzki belted a three-run homer and Charlie Blackmon added a two-run shot, pacing a Colorado offense that had been shut out in each of the previous two contests.
Jamie Garcia (4-2) was tagged with the loss, yielding five runs on eight hits in six frames.
Matt Adams and Pete Kozma provided ninth-inning RBI for St. Louis.
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