Low risk (1yr deal, small money), high reward (potential for a great back-up, receiving threat, injury insurance) type deal for the Pats. Let's face it, these jerks have been so good for so long that any veteran looking to get a ring or redeem themself goes there for peanuts.
Maybe someday when we establish a winning history, veterans will want to come here and not make us break the bank to get them (see this year's free agent thieves).