"In an ideal world, Orioles president of baseball operations Andy MacPhail would introduce the organization's top pitching prospects to the major leagues at different points of the season. However, with four of the five members of his Opening Day rotation no longer part of the starting staff because of either injuries or ineffectiveness, he has been left with little choice.

Rookies Brad Bergesen, Jason Berken and David Hernandez are already part of the rotation, and Triple-A Norfolk right-hander Chris Tillman, 21, appears to be the next man up if another injury occurs or the struggles of Berken or Rich Hill persist. Tillman threw 7 2/3 shutout innings Friday, striking out seven and allowing just four hits and a walk. He improved to 6-5 with a 2.69 ERA.

"I've always said, you want to make sure when they get here, they have a reasonable chance to succeed, but sometimes events dictate what happens," said MacPhail, not speaking specifically about Tillman. "Things don't always go as planned. Things change. We have to go with events and make the best decisions that we can in the context of the current times."

MacPhail said he is not looking for the current rotation to change, but if it does, he would prefer summoning one of the Orioles' prospects rather than calling on a well-traveled veteran. The Orioles' Opening Day rotation included Koji Uehara, Adam Eaton, Alfredo Simon and Mark Hendrickson, joining holdover Jeremy Guthrie. But Guthrie is the only one who remains. Eaton was released, Simon is out for the season after having Tommy John ligament-reconstruction surgery and Uehara is out until at least September with a partially torn tendon in his pitching elbow. Hendrickson is currently in the bullpen.

"We had our share [of turnover] already, but we've been able to fill in with guys like Bergesen and Berken and Hernandez as opposed to going down and getting veteran guys who are kicking around," MacPhail said. "Frankly, we had our [veterans] at the beginning just to give us some time to help us make the right decision with the minor league guys. I'm hopeful we have enough young candidates down below where we won't have to resort to guys that are clearly in the twilight of their careers.""