The Astros placed McCullers on the 15-day injured list Tuesday with right shoulder inflammation, Matt Kawahara of the Houston Chronicle reports.
Manager Joe Espada said McCullers' shoulder issue is something he's been dealing with for a while. The right-hander didn't bounce back from his most recent start the way the Astros had hoped, so they'll now opt to place him on the shelf and send him back to Houston for further evaluation. A timeline for his return will likely be established once his test results come back.