He is not close to a return to the big leagues. The next step in his rehab from left shoulder tendinitis is expected to be a step up to another Minor League level, much like Al Alburquerque did in his rehab assignment.
That doesn't rule out a closing stretch in the big leagues for Schlereth, who could give Detroit a situational left-hander if he's commanding his pitches better than his early-season stint before he was injured, and probably better than the stats suggest he did on Saturday. Given the roster situation, though, that promotion might not come until rosters expand in September.
Schlereth could still conceivably make the postseason roster under that scenario, since he was on the Major League roster earlier this season and then went onto the disabled list in the big leagues, not Triple-A.