The defense last year, after week 3 allowed the 3rd fewest points in the NFL. Does that suck?
Looking at points given up is misleading.
Last year, the Pats gave up a total of 10 turnovers all year. That's amazing, but moreover it meant that the defense was almost never put under stress from bad field position. The Pats offense made it as easy as it can get for its defense. Most other NFL defense didn't have that luxury.
Also, points don't include pick-6 or fumble returned for td, or TD on special team. Looking at that 3rd fewest point stats is reflecting on the whole team, not just the defense. And I think that last year, with the offense being in top 5 all-time, they carried a lot more weight than the defense did.
This year, the offense is less dominant. They are giving up turnovers, and as we saw on Brady's fumble against the Giants, the defense was very quick in 'converting' the offense mistake into a TD.
Defense should be evaluated on efficiency, not on volume stats like points given up. I don't care if the defense played well enough to go into the 4th quarter with a 10-3 score. What I want to see, is when the game is on the line and the defense is on the field, can they get out with the win ? At this time they can't. On the other side, with the game on the line and the offense on the field, even though the Pats offense had been terrible against both the Giants and Cowboys for most of the game, they delivered a TD each time on their final drive.
It's all about efficiency, not volume. On a given situation, can they execute or they can't ?