Drew will occupy a Major League roster spot until the Red Sox send him out, which means the move will likely happen soon, perhaps as early as Friday.
Manager John Farrell said that the Red Sox would likely use Drew's roster spot for a reliever for the next two games, and then for a starting pitcher to replace the injured Felix Doubront on Sunday.
As for Drew, the Red Sox are weighing several things before deciding which affiliate he will go to. After he gets about 25 at-bats, Drew will rejoin the Red Sox.
"We're looking at schedules, we're looking at who is in certain cities," Farrell said.
Ian Browne is a reporter for MLB.com. Read his blog, Brownie Points, and follow him on Twitter @IanMBrowne. This story was not subject to the approval of Major League Baseball or its clubs.