So what happened to The Legion of Boom? Atlanta's high-octane offense, for one, but also a string of key injuries to Seattle's once-impervious secondary.
"He has some regrets about this season," Carroll told reporters.
The injury comes as a surprise since Sherman was not listed on the Seahawks' official injury reports with the ailment.
"Honestly, I didn't even know we didn't report," Carroll said during his Monday news conference, via The News Tribune. "I'm feeling like I screwed that up."
NFL Network Insider Ian Rapoport later confirmed that Shead is set for surgery to repair a torn ACL, with a source noting that the cover man is likely looking at an eight-month recovery window. The 28-year-old cornerback is set to become a restricted free agent in March.
Shead was lost in the second half against Atlanta, only thinning a secondary already missing All-Pro safety Earl Thomas. The injuries made a challenging matchup all the more disastrous for Seattle -- and the 'Hawks weren't up for the task.