Seahawks coach Pete Carroll revealed that cornerback Richard Sherman had a significant MCL injury the second half of the season, a Seattle Times reporter tweeted on Monday.
An MCL injury is a sprain or tear to the medial collateral ligament, which is a band of tissue on the inside of the knee.
Sherman demonstrated combative behavior on and off the field before the Seahawks' playoff loss Saturday to the Atlanta Falcons.
His outbursts during games have made headlines throughout the season. In December, during a game against Los Angeles, Sherman yelled at Carroll and offensive coordinator Darrell Bevell for a decision to have quarterback Russell Wilson throw a pass from the 1-yard line that was nearly intercepted.
Sherman did not back down from his stance a few days later at a weekly news conference and offered no apologies. During the same news conference, Sherman threatened to "ruin" the career of a radio reporter as he left the room, a comment for which he later apologized on Twitter.
Sherman had a public sideline meltdown in October, but weeks later he lightened the mood by dressing as Harry Potter during a news conference. Sherman said the costume was for his son.
Months later, Sherman stopped talking to local media and ended his weekly press conferences, saying it was a “privilege” to talk to him.
SeattlePI.com reporter Stephen Cohen reported that Sherman was on the practice report for 11 weeks during the season; 10 were “non-injury related” and one was for an ankle injury. Cohen reported that a knee injury was never mentioned.
Sherman has spoken openly against the NFL and its treatment of players.
Sherman opened up in a column and video on The Players Tribune in September about what he calls a huge issue that many players talk about behind closed doors.
"As we players are to this game, it's getting more and more difficult to ignore the fact that we don't have a league that shows the same kind of dedication when it comes to taking care of the players who are laying their bodies on the line every Sunday,"<br/> <a href="http://www.theplayerstribune.com/richard-sherman-seahawks-how-we-play-football-in-seattle/" target="_blank">Sherman wrote</a>.
Some people said Monday on social media that Sherman’s knee injury “explains a lot” during the latter part of the season.
But Seattle Times columnist Matt Calkins wrote that the team – from Sherman's behavior to Michael Bennett's post-game tirade – has shown a lack of grace during the 2016 season in the way it handled losses and took criticism. Read Calkin's column here.