NE played a very very weak schedule is the bottom line.
And they have not faced a good "O". Pittsburgh has played a much stronger schedule (# 11 vs # 32) but Pittsburgh actually has not faced any top "O's" or QB's, either (Flacco? Brady, yes, but Pittsburgh did not have Ben).
IMO the issue is that the NE "D" is overrated because of their weak schedule and not having faced a good passer.
IMO NE offense is strong, but the "D" is a big ??????
Pitt has jelled on "D", their "O" is good, will Bellicheat find a way to take out Brown and / or Bell?