Manager John Farrell said that Bradley will play center field every day while Betts bounces back from the concussion he suffered in Tuesday night's 9-4 loss to the White Sox while falling over the bullpen wall.
"Obviously it was confirmed consistent with the symptoms last night and the further testing -- it's clear he has a concussion," said Farrell. "Timetable for this is unknown, but every available test to rule out anything else from the upper back to the neck obviously to his skull, all that was performed and everything else has been ruled out other than the fact that he has a concussion."
Bradley has had a solid year at Triple-A, and the Red Sox hope it can translate to the Major Leagues. This is the fourth time Bradley's been called up this season, but the first he will get a chance to play every day.
"I'm playing ball," said Bradley. "Trying to let the game play for itself, take care of itself. I turned the page and feel like I'm on the right track."
Bradley spent most of last year with the Red Sox and had a stellar year with the glove but a tough one with the bat.
The outfielder made adjustments to his swing and had success with the Red Sox during Spring Training.
"You see it in the swing path," Farrell said, "and his performance in Spring Training is consistent with maybe closing up some of the holes that emerged last year. It's been able to be carried over while at Pawtucket and now it's a matter of being able to do it against Major League pitching."
Ian Browne is a reporter for MLB.com. Read his blog, Brownie Points, follow him on Twitter @IanMBrowne and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.