Defensive tackle Darnell Dockett, who spent the season cheering on teammates from the sideline because of a knee injury, was released by the team Friday. He could still return.

Darnell Dockett isn't on the Cardinals roster for the first time since 2004.

The veteran defensive lineman could still come back, however.

The Cardinals released Dockett Friday after the team and the player couldn't come to a new contract agreement and with Dockett slated to carry a $9.8 million salary cap number into the final season of his current contract. With free agency starting March 10, the move allows Dockett to gauge his worth on the NFL market.

"We have been very clear about our feelings for Darnell and our desire to have him back," General Manager Steve Keim said in a statement. "After speaking with him and his representatives, we decided that this move today makes the most sense for

both the team and the player and allows each to keep all of its options open."

Those options include Dockett's return to the team.

Dockett, who will be 34 in May, is coming off an ACL tear in his knee that kept him out the entire 2014 season. Up until this past season, Dockett had only missed two games in 10 previous years with the Cardinals. In his career, the one-time third-round pick has made three Pro Bowls, the most recent after the 2010 season.

His salary for 2015 was scheduled to be $6.55 million. His release brings with it $3 million of dead money, although the Cardinals will save $6.8 million of cap space with the move.

A return after a release is not unprecedented. The Cardinals cut tackle Levi Brown in 2012 because of an unwieldy contract. Brown was briefly on the free agent market before re-signing with the team.

Right after the season ended, Dockett acknowledged something like this might happen.

"Do I want to leave Arizona? No," Dockett said in January. "But if I had to, despite being frustrated having to go somewhere else, I would. I can't say I would be happy with the situation if that decision if it was made, but I understand this is a business. It's happened to the best of them. At the end of the day my loyalty is to Arizona."

Earlier this week, Dockett tweeted out "No matter the logo, I'm going to win Comeback Player of the Year."

As of now, the Cardinals have work to do to shore up numbers on the defensive line. Aside from Dockett, Tommy Kelly and Dan Williams are both scheduled to be unrestricted free agents. Alameda Ta'amu will be a restricted free agent.