PITTSBURGH -- When general manager Neal Huntington announced the acquisition of Aki Iwamura in October, he was asked about the second baseman's surgically repaired left knee. Would it affect Iwamura's range? Might it still linger in 2010?

At the time, Huntington said he was confident that the injury would present no problems a year later. Now, though, Huntington concedes that it could be part of the reason for Iwamura's disappointing season start.

A .281 hitter in three seasons with the Rays, Iwamura entered Sunday hitting just .194 with a .294 on-base percentage. He has just two hits in 20 at-bats so far this month.

"He cares, and like most professionals when they struggle, they begin to make their problems worse because they begin to try too hard," Huntington said.

The knee, though, has appeared to be an even bigger issue in the field. Iwamura has shown a lack of defensive range, and he has been slow to turn double plays, particularly on the receiving end of the shortstop's feed. It was while turning a double play last year that Iwamura was taken out and suffered a torn ACL. That could explain some of his hesitancy now.

"The knee is probably a bigger factor than we recognized in September, just in terms of confidence," Huntington said. "I think that the contact on the double play -- using the bag as a shield rather than coming through on the double play -- that's human nature. I know [infield coach] Carlos [Garcia] will continue to work with him to do the things he needs to do to maximize his ability to put something on his throws and also protect himself."

Karstens headed to Bucs' bullpen

PITTSBURGH -- Jeff Karstens' spectacular outing on Saturday has earned him a stay in Pittsburgh, but it will be as part of the club's bullpen.

Manager John Russell confirmed on Sunday that Brian Burres will remain the team's fifth starter for now, meaning that Karstens will be the one knocked out of the rotation when Ross Ohlendorf returns from the disabled list on Monday. But rather than sending Karstens down to Triple-A, where he could continue to start, the Pirates believe he can be an asset here in relief.

"We'll make the switch now and see where we go," Russell said. "It was just going to be too much time between his next start, so it makes more sense to utilize him in a bullpen. You can use him any way you want. It gives you a lot of flexibility."

Burres, who has made consecutive scoreless starts, will take the mound next on Friday in Chicago. If he isn't able to continue his current string of success, the Pirates always have Karstens as a fallback option to jump back into the rotation. Prospect Brad Lincoln is waiting at Triple-A, too, as another potential option.

"It's not been an easy decision," general manager Neal Huntington said. "It's amazing to think about where we were two or three weeks ago, and now we get somebody who probably deserves to stay in a rotation based on a couple starts and stuff that they've shown. That's a great situation to have. It's what we thought we were going to have out of Spring Training, and it just didn't work out that way."

Karstens' move to the 'pen is likely to cost Brian Bass his spot there. The Pirates will have to open up a roster spot for Ohlendorf on Monday, and Bass is expected to be sent back to Triple-A Indianapolis to create that opening.

Jakubauskas suffers setback in recovery

PITTSBURGH -- Right-hander Chris Jakubauskas has been shut down from baseball activities again after suffering a minor setback on Friday.

Jakubauskas, who was diagnosed with a concussion and head contusion after being hit in the back of the head by a line drive on April 24, had been headache- and dizziness-free for days until Friday. After playing catch and doing some other light activity that day, Jakubauskas experienced some dizziness when he sat down.

That was enough for the Pirates' medical staff to tell the right-hander to cease all physical activity until further notice. Jakubausakas, who had just resumed basic exercising on Monday, is scheduled to have a follow-up visit with a doctor soon, too.

Donnelly won't be ready for road trip

PITTSBURGH -- Though injured right-hander Brendan Donnelly (strained left oblique) continues to progress, the Pirates are not anticipating having him available until the team's next homestand, which begins on May 19.

Donnelly is eligible to come off the disabled list as early as Thursday, and initially, the belief was that he would be ready to return by then. However, Donnelly's conservative track back from the injury simply won't have him ready that quickly.

Donnelly, 38, played catch indoors on Sunday. The next step will be to have him play catch and throw long toss outside this week before getting a few side sessions off the mound under his belt. Manager John Russell said Donnelly might throw in a simulated game, too, before returning.

"He's progressing," Russell said. "I think it would be a stretch to get him back before we get off the road."

In 11 appearances this year, Donnelly has allowed seven earned runs on eight hits and 10 walks in nine innings. All of those runs were scored in two appearances.

Worth noting

Pirates players and broadcasters will head to the Noble Manor AMF Lanes in Crafton, Pa., following Sunday's game to participate in the sixth-annual Bowling with the Bucs charity event. Pitcher Zach Duke and his wife, Kristin, are hosting the event, which will raise money for Pirates Charities. ... Though right-hander Kevin Hart still has a long way to go to recover from right shoulder surgery, general manager Neal Huntington said on Sunday that the organization still plans to use him in a starting role once he returns next season. ... On Saturday, right-hander Michael Crotta made his second start since being promoted to Triple-A. Though he was tagged with the loss, Crotta went eight innings, allowing four runs on eight hits.