Buchholz began that assignment for Pawtucket on Sunday, giving up three hits and a run over four innings.
The actual injury -- a broken nail on his throwing finger -- wouldn't have necessitated a trip to the disabled list in most cases. But it came at a time the Red Sox were decimated by other injuries, and needed to open up a roster spot for another position player.
During Buchholz's sabbatical, Bartolo Colon has taken his spot in the rotation. As long as Buchholz is pitching in Minor League games, the Red Sox will try to make it a developmental experience for the right-hander.
"He's working on a little bit of getting away from his head to try to create some movement with his fastball," said Red Sox manager Terry Francona. "He had that arm slot when he signed. Just trying to get some consistency with that and take advantage of these innings where he's not here. But he sounded real upbeat."
Taking a regular turn in Boston's rotation before the injury, Buchholz went 2-3 with a 5.53 ERA.
Buchholz's next turn for Pawtucket will come on Friday at Durham.
"We talked to Buchholz today about his next start," Francona said. "Wouldn't want to get ahead of you guys with that when we haven't with him."
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.