Are the New England Patriots psyching themselves out?

One mystery to me is why the Patriots are not pressuring the opposing quarterback more than they have done over the past several years.

Belichick's New York Giants defense was known for pressuring the QB.  But not these Patriots.  I have a few theories:

1) The amount of salary cap spent on the offense is higher than what Belichick's Giants spent for defensive talent
2) Sacks, especially, are an overrated statistic (a la Moneyball) while QB hurries and interceptions are more win-producing
3) Having a higher scoring offense means less emphasis on defensive performance

But after yesterday's bitter loss to the surging Buffalo Bills, I have come up with a new theory:

4) The Pats subconsciously HATE when Tom Brady gets beat on (a la SuperBowl XLII).  So they can't emphasize beating the other QB.  Or they don't want to beat on that QB, and have the team tit-for-tat come after Brady.

If that is the case, I think Belichick needs to get over it.

I think the Patriots like to get after a particular defense by gameplanning matchups.  They will also go after the essential key skill player in an offense, such as a running back (e.g. Marshall Faulk in XXXVI) or tight end (e.g. Antonio Gates last week).

When was the last time they got after the QB directly, and not his receivers?

DISCLAIMER:  What the heck, do I know?  I haven't played organized football since middle school, which was not tackle but flag football.