Smith was optioned to Triple-A Las Vegas on Tuesday.
Smith was called up from Las Vegas on Sept. 5 and played in 15 games during his three weeks with the big club, but he failed to take advantage of the playing time with a .544 OPS and 38.6 percent strikeout rate in 41 at-bats. The 27-year-old has a .185/.220/.326 slash line over 146 plate appearances in the majors this season and is now likely to close the campaign with those figures.