Seattle had 5+ years as an elite unit with Sherman/Thomas/Chancellor/Wagner and that's nearly the quality you're lining up with Mack/Smith/Amos/Floyd/Hicks/Goldman/Fuller also, PFF fwiw: But didn't Seattle build their defense (nearly) entirely through the draft over a ~2 year period? They didn't have big money free agents like Mack and Hicks. The Bears have Smith and Floyd on relatively cheap rookie deals but the rest are all big money and 26+. Adrian Amos is likely gone this offseason, given the extensions and contracts they've already had to spend on everybody else. Two things work against prolonged greatness on defense. 1) While an offense can theoretically rely on a QB to drive the entire engine and mask the weak spots, defenses with weak spots will get exploited. An elite defense takes a whole bunch of elite money making players. 2) Elite defense relies heavily on youth. You don't veteran savviness your way to elite D. And football youth is especially fleeting. When we look back at this era you're going to start with last season as the first good one, this year potentially the first elite one, and then maybe 2 more years near the top. But they will have a very tough time restocking the defense to keep it elite in 2021. They are going to have a lot of pressure making sure they get something out of the 3/4/5 picks in 2019, then they have to hit on the the 2/4 in 2020. It's going to be very tough to maintain.