The Mariners optioned Emerson to Triple-A Tacoma on Thursday, Ryan Divish of The Seattle Times reports.
Emerson hasn't quite lived up to the expectations that come with being a top prospect since arriving in the majors in May, slashing just .190/.246/.335 across 241 plate appearances while striking out at a 34.4 percent clip. The Mariners will now send him back to Tacoma in an effort to help him rediscover his swing, leaving Leo Rivas as the favorite to start at shortstop until J.P. Crawford (wrist) returns from the injured list.