Boxberger (oblique) isn't expected to return from the disabled list until the end of next week at the earliest, Marc Topkin of the Tampa Bay Times reports.
Boxberger has already made three rehab appearances with High-A Charlotte during his current DL stint, but the Rays want him to put together an extended stretch of quality outings in the minors before bringing him back to the big league bullpen. Even though he saved 41 games for the Rays a season ago, Boxberger has missed too much time in 2016 to pose a serious threat to Alex Colome's standing as the club's top closer.