Triple-A Norfolk placed McDermott on the 7-day injured list Tuesday with a right scapula stress reaction, Rich Dubroff of BaltimoreBaseball.com reports.
McDermott's last appearance for Norfolk came back on July 30, and he struck out 10 while yielding just two runs over six innings. However, the right-hander evidently picked up an injury during or after that outing and now appears likely to miss multiple weeks.