Shead's knee buckled as he attempted to cover Falcons receiver Taylor Gabriel on a comeback route near the sideline in the third quarter. As Gabriel made his cut, Shead's knee gave away and he ultimately was taken to the locker room on the back of a cart.
"It was a significant ACL injury with some of the other things that normally happen," head coach Pete Carroll said.
Seattle wide receiver Paul Richardson sustained an ACL injury on this weekend two years ago and began the 2015 season on the physically unable to perform list. He ultimately missed the first nine weeks of the season before returning to Seattle's roster. While the recovery process can vary based on the individual, it seems unlikely to expect Shead to be ready for the start of next season.
Shead will be a restricted free agent for Seattle. The Seahawks will have to place a first-round, second-round or original round tender this offseason if they want to keep him for next year. As Shead was initially an undrafted free agent, the Seahawks would not be entitled to any compensation should he sign an offer sheet with another team after being given a restricted tender by Seattle.
"It's going to be all the way until next season before he really gets to start seeing how far along he is and if he can come back so we have to think like we got to pull from the ranks of the guys and see how they do," Carroll said.
Shead started 15 of 16 regular season games for the Seahawks this year, his first year starting full-time at cornerback for Seattle. He had 81 tackles, a forced fumble and an interception.