Van Benschoten, recalled from Triple-A Indianapolis, where he was 4-0 with a 1.88 ERA, will pitch in long relief for the Bucs.
Dumatrait, who had been pitching in long relief and was 0-1 with a 4.32 ERA, moves into the starting rotation.
"Phil has been throwing the ball well for us and he's obviously been a starter," Pirates manager John Russell explained. "We've kept him pretty stretched out already this season. I think he'll be able to step in that role and do very well. He's capable and we're not going to have to build him up, we have extended him a little bit."
For Dumatrait, it is a second chance to start. He was 0-4 as a starter last season in Cincinnati and posted a 15.00 ERA.
"The first go-around last year in Cincinnati didn't go that well," Dumatrait offered. "I'm looking for the opportunity, and I want to go out there and prove that I belong as a starter."
Van Benschoten, the Pirates' first pick in the 2001 First-Year Player Draft, is happy to be back for another shot in the big leagues. He was 0-7 with a 10.15 ERA with the Pirates last season.
"I'm really feeling good about this," Van Benschoten said. "I was really feeling good in Indianapolis and it's good to be back here, and it's just seems a little more upbeat and it's a different feel, I think. I think it's a mental state, and it's just trusting it and being able to attack the down part of the zone. That's what I did at the start of this year and it's been effective, and it will be effective here."
George Von Benko is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.