The Astros optioned Contreras to Triple-A Sugar Land on Monday.
Contreras earned a spot on the Astros' Opening Day roster, but across four bullpen appearances he's logged an 8.44 ERA and 1.69 WHIP in 5.1 innings. He'll look to regain his form in the minors while Logan VanWey gets the call-up from Triple-A in a corresponding move.