They're a dynasty based solely on longevity. They've remained really good for a long time. I guess the reason they don't seem like an actual dynasty (besides the multiple times they';ve been caught cheating) is the fact that they are never a dominant team that is genuinely feared like the great Steelers, or 49er, or Dallas teams. They are the Rafeal Palmiero of football teams. There's never a year that they seem obviously better than anyone else. It's just a cumulative thing based on how long Brady has been there and they've remained really good. In fact, the one year that they actually did seem dominant (2007), they didn't win the Super Bowl. They've really been a great team who keeps winning Super Bowls by 3 points, ort because of terrible opposition play calling (Seattle) or total opposition choke jobs (Atlanta). Obviously there's something to be said for being able to maintain this 'really good'ness for so long. A combination of Belichick being a great coach and Brady staying healthy for so long. But they're not your tradition dynasty where teams have a fear of you because you stand head and shoulders above everyone.