CHICAGO -- Left-hander Jorge De La Rosa was signed by the Cubs on Friday after the D-backs released him earlier this week. Manager Joe Maddon said the 37-year-old was available to pitch out of the bullpen for the Cubs' series opener against the Nationals on Friday afternoon at Wrigley Field.
"We were just trying to augment that left-handed side coming out of the bullpen," Maddon said. "Plenty of experience. He hasn't pitched in several days. He's definitely ready to go. It creates more depth."
In corresponding moves, Chicago assigned lefty Randy Rosario to Triple-A Iowa and placed right-hander Yu Darvish on the 60-day disabled list, retroactive to May 23. Darvish had been on the 10-day DL for more than 60 days, and the Cubs said that placing him on the 60-day DL was "purely procedural" to make room for De La Rosa on the 40-man roster.
A 15-year veteran, De La Rosa pitched in 42 games this season with Arizona. He went 0-2 with a 4.63 ERA, a figure largely skewed because of a seven-run outing against the Rockies in Colorado on July 11. His ERA in his other 41 appearances is 2.97.

The lack of left-handed relievers seemed to be the Cubs' only significant hole in their otherwise steady bullpen, which now features De La Rosa and Justin Wilson as the two lefties.
Against lefties this year, De La Rosa has been consistently strong, limiting them to a .220 average (13-for-59). Because of this, at least at first, Maddon said De La Rosa is mostly "here for lefties."
"A bad outing or two that really can blow up a relief pitcher's numbers," Maddon said. "I've seen him in the past throw well against righties. I'll evaluate where he's at right now. But you'll see him primarily in a lefty slot, maybe a matchup lefty one on one."
A specific role isn't important to De La Rosa, who said he's willing to take the ball whenever he's needed.
"I was pitching in any situation in Arizona," De La Rosa said. "I think it will be the same here."
De La Rosa has previous relationships with two other Cubs pitchers, Tyler Chatwood and Mike Montgomery. De La Rosa and Chatwood were teammates with the Rockies for five seasons, while he and Montgomery worked out together in the offseason.

"There were times when we were paired up and I was having to take some weight off," Montgomery said of the winter workouts with De La Rosa.
"He's built like a bull. He's got a good arm. That's why he's in his [late] 30s and still doing it."
Rotation changes
With a day off Thursday and another one coming up Monday, the Cubs are going to delay Montgomery's next start until Saturday, Aug. 18, on the road vs. the Pirates.
Kyle Hendricks, Jonathan Lester and Cole Hamels will start this weekend against the Nationals, with Jose Quintana now scheduled for Tuesday's series opener against the Brewers and Hendricks set to start again on Wednesday.
In the meantime, Montgomery will be in the bullpen this weekend, though his availability for Friday's game was uncertain.
Chatwood's role in bullpen not specified
Maddon said Friday that he's not entirely sure of the role Chatwood will have in the bullpen, where he's been since the Cubs acquired Hamels at the end of July.
"We're still trying to evaluate that and make it work," Maddon said. "I can't tell you there's a specific spot right now for him. I'd just be making stuff up.
Chatwood has made two relief appearances since going to the bullpen, his latest coming Wednesday against the Royals, when he threw 1 1/3 innings and allowed four runs. On Aug. 1, he pitched a scoreless inning vs. the Pirates, but he allowed one hit and one walk.
"I need to get him out there so he can get his feel coming out of the 'pen," Maddon said.
Chatwood's time in the rotation was not what the Cubs had hoped when they signed him to a three-year, $38 million deal this offseason. In 19 starts, he went 4-5 with a 4.98 ERA. He had walked 85 batters in 94 innings pitched as a starter.