The Pirates placed Peters on the 15-day injured list Thursday due to left elbow inflammation, Alex Stumpf of DKPittsburghSports.com reports.
Pittsburgh brought up left-hander Eric Stout from Triple-A Indianapolis to replace Peters on the 26-man active roster and in the bullpen. Peters previously missed time with a back muscle spasms before being activated July 12, but he made only five appearances before the Pirates deactivated him again.