SB nation reporting that he could be a victim of the cap. Twitter account shutdown cited as evidence. That's not really good evidence. In fact, it's not evidence. He was the MVP of the defense last year, can't imagine they let him go.

http://www.behindthesteelcurtain.com/2013/1/28/3924364/steelers-roster-rumors-release-retire-ryan-clark-2013-salaary-cap-nfl