"De La Rosa is a crafty reliever who has had some success in the upper Minors and in a short Major League stint," said Padres assistant general manager Josh Stein.
"He's likely a left-handed specialist but does have four pitches and relies on mixing all of them and changing speeds rather than pure velocity."
De La Rosa, 25, made his big league debut with the D-backs in 2013. He was 2-0 with a 2.95 ERA in 19 appearances for the D-backs last season. He was traded to the A's in December before he was acquired off waivers by the Dodgers on April 30.
To make room for De La Rosa on the 40-man roster, the Padres moved right-handed pitcher Josh Johnson from the 15-day disabled list to the 60-day DL.
This, essentially, equates to a paper move to create a spot on the 40-man roster, as Johnson continues working his way back from Tommy John surgery. Johnson was originally placed on the 15-day disabled list on April 5, meaning he's eligible to come off on June 5.
Johnson threw a bullpen session at Petco Park on May 19 and reported some soreness in the triceps area. He also had triceps tightness after a simulated game on April 28.
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.