The Red Sox designated Cooper for assignment Tuesday, Christopher Smith of MassLive.com reports.
Cooper got a shot at fairly regular reps with the Red Sox between first base and designated hitter, but it didn't work out, as he slashed only .171/.227/.229 with a 22:3 K:BB over 75 plate appearances. He'll get a shot somewhere else if he winds up leaving the Red Sox organization, but Cooper might have to spend some time in the minor leagues first.