He won't see any playing time at QB, obviously. But, New England may just be the best fit for him right now. He's with his old OC that drafted him in Denver, he'll get to learn from one of the greats in Brady and he'll be around an organization that is arguably the best in the league. Even if that never gets him on the field in Foxboro, it may prepare him for an eventual "comeback" with another team in a year or two. We'll see.
He came into the NFL in 2010, 2 more years til the comeback that puts his comeback in 2015. That puts him at 27 and 5 years removed from seeing the field. Good luck with that.