The Yankees once-stellar three-man back-end of the bullpen is now down to one, at least temporarily. David Robertson has been placed on the 15-day disabled list with a strained left oblique muscle, the Yankees announced Tuesday afternoon.

Robertson, 27, hadn't pitched since May 11 due to the oblique issue. He had yet to allow a single earned run until his May 9 outing against the Rays, when he blew the save and allowed four runs. Still, that's the only time this season he's allowed any earned runs, and he has a 2.51 ERA with 24 strikeouts in 14 1/3 innings.

With legendary closer Mariano Rivera out for the season due to a torn ACL, that leaves Rafael Soriano as the closer. Not that this in and of itself is a big problem.

Soriano, 32, has successfully closed both of his save chances since Robertson has been injured. He has a 2.57 ERA with 13 strikeouts in 14 innings this season. Also, Soriano was one of the best closers in baseball for the Rays in 2010.

Where this really hurts the Yankees is the bullpen depth as a whole. With starting pitching being a problem so far this year, it had to have been comforting to only need to get a starter through six before seeing Soriano-Robertson-Rivera. Now Cory Wade and Boone Logan -- who are having quality seasons -- will be thrust into the seventh- and eight-inning roles, meaning the guys behind them will also be featured more prominently.

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