BALTIMORE -- For the second time in less than two weeks, the Yankees lost their closer.
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Robertson was sent back to New York in the morning and he was diagnosed with a strained left oblique, an injury the reliever said he first felt after Friday's appearance against the Mariners.
"We don't think it's too severe but it's hard to tell," Joe Girardi said. "Obliques can be tricky. We expect him not to pick up a baseball for probably 7-10 days, and then we'll see where we are after that."
That would make it unlikely that Robertson, who had one save and blew another since taking over for Rivera, will be back when the 15-day stint is up.
"It's really disappointing because it was something I was hoping would be a real quick recovery, two or three days hopefully, I'd be back, and it just hasn't gone away," Robertson said. "So I went and got it checked out today and turns out there's a reason it's not going away.
"They said it's very mild. It's one of those things, though, if I kept pitching, it was likely to get worse and if it gets worse, then I could be out for 6-8 weeks or something like that and that's the last thing I want to do."
Soriano shut down the Orioles on 15 pitches Monday night for his second save.
As one scout pointed out, the Yankees could have done far worse in turning the closing duties over to someone who two seasons ago saved an American League-best 45 games with a 1.73 ERA.
"He's a guy who's done it before," the scout said. "Some guys just can't handle it. He's proven he can."
Soriano, 2-3 with a 4.12 ERA last season, hinted that part of the reason he got off to a slow start was because he didn't have a clear role.
For the time being, Soriano's role is defined and he didn't try to hide his enthusiasm. "I love it," said Soriano, who has 92 career saves. "I like the situation to be tight. That [the pressure] is what I like. I know what I got, everybody knows what I can do," he said. "I feel fine with that."
Girardi will have to shuffle his bullpen as Boone Logan, Cory Wade, Clay Rapada and even long man David Phelps will have to face far more late-inning situations than before. "Guys' roles have just increased a little bit," Girardi said. "I have no eighth-inning guy. I have a ninth-inning guy and then I have a bunch of innings."
Righthanded reliever Cody Eppley was recalled from Triple-A Scranton/Wilkes-Barre to take Robertson's place on the roster.