De La Rosa had his contract purchased from Triple-A Reno on Friday.
De La Rosa has impressed with Reno this season, compiling a 2.35 ERA, 0.98 WHIP and 23:4 K:BB over 15.1 innings of relief. He'll replace JJ Hoover on the active roster, while catcher Oscar Hernandez was designated for assignment to clear room on the 40-man.