While the Patriots obviously want Brady, the 2007 NFL MVP, back for the start of the 2009 season, the greater concern is how strong the knee will be when he returns, how long the knee will hold up, and how it will affect his play.

Brady, who turns 32 in August, and the Patriots likely will not have definitive answers to those questions until this summer, when the quarterback can test himself in game-like situations at training camp.

All the more reason for the Patriots to place the franchise tag on backup quarterback Matt Cassel, who proved a more than capable starter while filling in for Brady. The Patriots can’t franchise Cassel, preventing the QB from becoming an unrestricted free agent, until Feb. 5.

Still, the latest reports on Brady’s knee seem more encouraging than a month ago, when an NBCSports.com report said both the ACL and MCL were loose and a second reconstructive surgery would be required to repair the problem.

The report said the second surgery could cost Brady the 2009 season.

The Pats must franchise Cassel to protect themselves if Brady doesn’t recover. Sure, a lot of cap space will be eaten up at the quarterback position next year if they do tag Cassel, but it’s better to have him as a security blanket so if Brady goes down again, their entire season doesn’t go down the drain because they don’t have an experienced backup.

Tagging Cassel buys the Pats one year to figure out what they want to do long-term.