Well, with 37.5% of the season complete this seems like a perfectly natural place to examine where the Seahawks are "Things I Think I Think" style. In this article, I focus on the defense.
Again, I will use Football Outsiders stats from the first six games.
Whooo boy, has this unit come together or what? Put it this way. If styles make fights, I seriously doubt any defense will face tougher back-to-back fights than New England and San Francisco. Seattle played the equivalent of Mike D'Antoni's Phoenix Suns and Larry Brown's Detroit Pistons on short rest. Yet, you can't be terribly disappointed with their defensive performance.
Drives. Seattle has played five of the top 20 offenses in DVOA already. Yet this defense comes up smelling like roses on the drive efficiency metrics--easily top 10 on most. DVOA also loves this defense (ranked 2nd behind Chicago). Interestingly, the upside for this group (and, yes, there is still upside) is probably in turnovers (ranked 18th). Seattle hasn't been been impressive on a per drive basis at forcing interceptions or fumbles (ranked 19th in both).
Higher and more consistent offensive output is the surest route to more defensive turnovers. Teams turn it over when they play from behind. But, it is worth noting that the secondary and linebackers get their hands on lots of passes and have dropped a TON of catchable interceptions. I expect the interception numbers to improve.
Defensive Line. I still haven't decided whether I think the strength of the defense is here or the secondary, but this group has been impressive against the run: 4th in adjusted line yards, 7th in short yardage/goal line and stuffing runs. Against the pass Seattle is 15th in adjusted sack rate (with due caveats about attributing sacks to only the defensive line). The run numbers will come down a bit after San Francisco but this group is clearly one of the best in the league--and has played some big time offenses. I love the mix of talent, and we still haven't even seen Jaye Howard.
Linebackers. I don't know film the way some of my colleagues here know it. What strikes me about this group is its range and tackling ability. Seattle ranks 3rd and 2nd respectively in so-called "second level" yards (RB yards between 5 and 10 yards past the LOS) and "open field" yards (RB yards 10+ past the LOS). These two metrics likely tell us the most about linebacker play in the run game. In coverage, the group has generally been impressive despite struggling in some match ups. A concern is depth, particularly if Wright and/or Wagner gets injured.
Secondary. The secondary has rightly received a good bit of praise. If this isn't the best secondary in the league you can't fit a library card between this group and whichever is the best one. Having said that, I expect to see them convert more "deflections to steals" as the season progresses. If I have a concern it is that Earl Thomas is fundamentally irreplaceable. So an injury could be devastating.