Your implication seems to be that the great defensive teams of the past may have problems with any of the teams we played in the first half. And no I wouldn't compare us to great defenses of the steelers and the 1985 bears.
An alternative inference is that, somehow, the stats in the first are indicative oh w the team will play against much, much more difficult opposition.
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Don't get me wrong. I think that we have a top 5 defense, and one that is plenty good enough to take us deep into the playoffs, and have us competitive in the AFC championship game and the Super Bowl.