Says who? This was never about whether he was still good or worth his current salary, he is both for sure. But the question is whether he is worth a raise and/or guaranteeing the remaining $20M on his deal when he'll be 33 and 34 respectively. Another issue is a team would undoubtedly want assurance that he'd be willing to play out his current deal as is but there is really no way of giving that.
Ooooor what they need to do is cut XSF and Clark. Then trade Brown and raid the Dallas Cowboy's Practice Squad!! They have 2 OL on there that I really like; Nate Theaker and Kadeem Edwards