Reynolds was optioned to Triple-A Las Vegas on Wednesday.
The 26-year-old infielder had been recalled on June 16 but only logged four plate appearances in that span. With Zack Wheeler (biceps) landing on the disabled list, the Mets opted to add more bullpen depth rather than keep another bench bat around, so Reynolds will head back to the minors to make room on the active roster for reliever Erik Goeddel. Reynolds will likely continue to shuttle between the two levels as needed for the reminder of the season.