Seattle D is significantly better than Arizona's.
Seattle's D is better than the Cards on paper, but I think it was the 3-4 look with all of the disguised blitzes that really threw Cam off. I think he will be much more calm and make better reads against a more traditional defensive style (that he's seen 3 years in a row). That's not to say that I think we will score a lot of points. Seattle's secondary is rediculously good and their pass rush is adequate, but our strengths on offense match up well against them. Running game, mobile QB, pro bowl TE.
Cards defense is another kind of beast that our offense is not used to playing against and our coaches are not used to game planning for.
Not saying AZ's D is better than SEA, just saying the matchups and schemes for AZ are the reason Cam looked uncomfortable a lot of the game. The offense still managed to score 27 points.
Our D is on par with Seattle's. That means it will be a close game and one that we can win.
Does their D concern me? Yes, but not as much as GB's offense in Lambeau in January.