Peterson has been demoted to the Mets' bullpen, Anthony DiComo of MLB.com reports.
Peterson has had a disastrous couple months while splitting his time between starting pitcher and bulk reliever, holding a 5.57 ERA, 1.67 WHIP and 53:23 K:BB over 53.1 innings. He will be available to pitch in relief beginning Sunday. Sean Manaea is taking Peterson's spot as a starter/bulk reliever.