Brentz (oblique) is on a rehabilitation assignment with Double-A Portland, the Portland Press Herald reports.
Brentz, who has been limited by injuries since 2013, opened this season on the disabled list after straining a muscle in his left side, but is on the mend now. He's played two games on his rehab assignment thus far, going 2-for-7 with a hit in each game. When he's ready, Brentz will join the roster for Triple-A Pawtucket. The one-time highly rated prospect has been passed by several players in the organization the last few seasons, but he still possesses a good arm and a power bat.