Actually, while Belicheat* had final say over player acquisitions, for drafting and free agency he* relied mostly on Pioli, who built the cheatriettes* Superbowl* teams*.
We all know of Polian's genius, but I really don't see a vast difference in Polian's background before Ralph made him GM, and Brandon's. (Or, for that matter, between Brandon's and 30-year-old Theo Epstein when he led the Red Sox to their first World Series title since 1918 in '04.) And, while Littman and Overdorf, as financial guys, are certainly involved in contract negotiations, John Guy and Tom Modrak are still the most influential of Brandon's assistants regarding player personnel - of course with the help of Paul Lancaster, Doug Majeski, Rashaan Curry, Brian Fisher, Brad Forsyth, Shawn Heinlen, Buddy Nix, Matt Hand, etc.
In other words - I'm not sure what your point is, but since this is only Brandon's 2nd year as 'GM', I don't think you have one. At least not a valid one if you're trying to hang the last decade on Brandon. He may well turn out to be another Polian - let's wait and see.