Robles was sent down to Triple-A Las Vegas on Wednesday, Anthony DiComo of MLB.com reports.
Robles had another underwhelming outing during Tuesday's game, giving up two earned runs off three hits and three walks over 1.2 innings. The 27-year-old appeared in 16 games for the Mets this year, logging a pedestrian 5.03 ERA -- and a 7.17 FIP -- with a 1.58 WHIP across 19.2 innings of relief. This will mark his second stint in the minors in 2018, as he spent two weeks at the Triple-A in late April. In a corresponding move, the Mets recalled Chris Flexen.