"I wasn't expecting to get called up to pitch in the bullpen," Rosenberg said. "I was just going about my business [in Triple-A], trying to get better starting and going deeper into games."
While closer Jonathan Papelbon has been excellent when he has had the opportunity to finish games, many appearances from the Phillies' middle relievers have not been pretty. In addition to Valdes' ineffectiveness, veteran righty Chad Durbin has allowed 10 runs in 12 appearances for a 7.30 ERA.
"He's got more of a track record than the other guys," Phillies general manager Ruben Amaro Jr. said of Durbin. "He's going to have to pitch better. I think he knows it. How long of a leash he has, I do not know. But he needs to pitch better."
In seven starts in the Minors this season, Rosenberg was 1-3 with a 4.30 ERA, 24 strikeouts and 20 walks. Rosenberg also spent time with the Phillies last season, primarily in August and September.
Joe Savery and Michael Stutes were also Triple-A options with Major League experience, but Amaro said Savery could not be called up because he was not eligible after being optioned to Lehigh Valley on May 10. Amaro added that Stutes had been inconsistent.
That left the door open for Rosenberg.
"Most of our middle relievers have not been very good, so we'll see whether Rosey can come in," Amaro said. "The last time, he threw pretty good. He's stretched out so he can go long."
Though Rosenberg, who was a Phillies 13th-round Draft pick in 2008, initially struggled in the big leagues (his ERA sat at 13.09 after his first 14 appearances), he eventually found his groove. Last September, Rosenberg allowed just one earned run in 10 1/3 innings of work, while holding opponents to a .094 batting average.
His strong finish gave the Phillies a reason to believe in him in 2013, and it gave Rosenberg a reason to believe in himself.
"There will still be nerves; there are always nerves when you pitch," Rosenberg said. "But that experience last year definitely helps. How I pitched toward the end of last year definitely helped my confidence. I think it will help this time around."