Concerned that a mild injury could linger and leave them without an extra reliever, the Orioles placed right-hander Alfredo Simon on the 15-day disabled list Wednesday afternoon and recalled Jason Berken.

Simon said he strained his right hamstring while running before Tuesday's game. He had a similar situation last season when he injured his left hamstring and ended up on the DL.

"I was doing my work, working out and doing my sprints, and I felt a little pop in there," said Simon, who is 1-1 with a 3.14 ERA in five relief appearances this season. "I don't know how long it is going to take for me to get ready, but I don't think it is that bad."

He was hoping to avoid the DL but said he expects to be activated when eligible June 28 — the move is retroactive to Monday. Simon also missed the first seven weeks of the season while making up for a spring training lost because he was detained in the Dominican Republic as a suspect in a fatal New Year's Day shooting.

Given the inconsistency of the Orioles' rotation in terms of pitching deep into games and Tuesday's 11-inning affair, manager Buck Showalter said, he couldn't afford to have Simon unavailable for the next few days.

"I think it was an unknown with Simon, and he has a history of hamstrings, he's had [that type of injury] in the past," Showalter said. "We didn't feel like there was any given when he would be able to pitch again and know what we were getting."

So the club recalled Berken, who was demoted to Triple-A Norfolk on May 20 after compiling a 7.94 ERA in 15 relief appearances. Berken started four games for the Tides, going 0-1 with a 3.86 ERA. He hadn't pitched since Thursday.

"It was his time to throw, we have length there and he was pitching well," Showalter said. "He is on schedule to give us whatever innings the Blue Jays will allow him to give us."

Berken will be used out of the bullpen, but Showalter said he could be pushed into starting duty in the future if needed.

"It will be depending on what the needs of the team are," he said. "I wouldn't say [starting] is outside the realm of possibility. If we need to go there, we could with him. I'd feel comfortable doing that."

Berken said he doesn't care about his role so long as he is back in the majors. The 27-year-old right-hander, who was the club's best pitcher in the first half of 2010, said he thinks his demotion was a good thing.

"I feel like long-term, it could really benefit me because I would be able to work on stuff and make some changes, make some adjustments that I probably wouldn't have made up here. So I feel like I made the best of my time down there," Berken said. "By no means was I feeling bitter or upset. … I have no one to blame but myself. And I knew that I would go down there and work hard and try to get better."

Berken allowed two runs in each of his past two starts and credits the success with a change he made at Norfolk. Instead of pitching from the left side of the rubber, he moved to the right side. He said he believes it gives him more deception. Former Orioles pitching coach Mark Connor made the suggestion in spring training, but Berken was more comfortable on the left side.

Without the pressure of the big leagues, Berken said, he made the change and it worked for him.

"I moved over to the right side, my hand placement is a little bit different," Berken said. "Just small adjustments, and I think it simplified things a little bit in terms of movement of my hands and body as a whole."

Roberts has headaches

Second baseman Brian Roberts (concussion) woke up Wednesday morning with headaches and was told not to participate in workouts in Sarasota, Fla., Showalter said. He will be re-evaluated Thursday.

It's not considered a major setback because Roberts still isn't cleared to do baseball activities. He is hoping to get that green light Tuesday when he revisits concussion specialist Dr. Michael Collins in Pittsburgh.

"We hope we get to the point here, before the 21st, when he goes back [to Collins], that it is not an issue," Showalter said.