No, defenses by themselves don't win championships, TEAMS do. It takes a total TEAM effort to win a ring, and there are various ways of winning one. Sure, having a great D like the Broncos had this past season definitely helps, but they would not have won if the offense didn't play conservatively and let the D and ST carry them.
For OUR team, our O is our key. IF our O is able to play with the identity they are trying to form (run heavy & ball control) then our D is not going to be tasked with as much of a heavy burden. If we can get just solid production from our D on the time they are actually on the field, that is a huge plus to our chances of winning.
Not to mention, ideally, they are more fresh because of our O controlling the ball and the clock. It then shouldn't matter if we have a dominant defense, just that they don't totally **** the bed every time they see the field. And let's face it, last season to my naked eye, our D was pretty solid until they gassed out late in the 2nd half of games.
Winning a championship requires a team to be in unison, to have a gameplan and understanding of what they as a TEAM need to do to produce a favorable result.
There are multiple ways to reach a destination.