It seems that most teams would fear Welker, Hernandez and/or the run game more than Lloyd or other threats -- all the more if the game is played on a windy night.
The Ravens, further, must be thinking that having a weak run defense "isn't them", and they should be able to fix it.
Proceed from there?
If I'm the Ravens, here's how I try to defend the Patriots.
First, play an extra DB and take out a LB. They will need more speed on the field to deal with the Pats' passing game.
Second, I realize that this makes them vulnerable to the run, but they just have to hope that guys like Ngata, Cody, and McPhee hold up stoutly against the run, which they are capable of doing, by the way. Trust them to have big games.
Third, I really try to take away the short-mid range passes in the middle of the field. Use the two LBs that I have left to clog the middle and force guys like Welker and Hernandez out wide. The Patriots kill teams over the middle.
Fourth, I play tight press coverage across the board and, especially in what looks like windy conditions, make the Pats try to throw deep. Along with that, I try to bring lots of pressure, especially up the middle to get in Brady's face. Force them to make quick throws, but be playing press coverage. If they blitz and stay back in a soft zone, Brady will annihilate them. So force Brady to get rid of the ball quickly, but hopefully choke off the quick routes and make them go over the top.
Fifth, try like crazy to control the tempo with the defense. Every tackle, lay on the Pats' ballcarrier for an extra couple of seconds, which gives us more time to get a substitution in if necessary. Delay, delay, delay, and emphasize getting off the field on 3rd down.
They have the talent to do the things I list above. When they are playing well, the Ravens' D is a handful. But all these things really have to break right. For example, if they do everything but Ngata and company cannot control the line of scrimmage, the Pats will run right over the smaller, faster Ravens lineup. Or if they try to bring pressure but the Pats succeed in picking it up, Brady will slice and dice them. Or if they try press coverage and Welker, Lloyd, and Hernandez beat it, they'll have a field day. You get what I mean.
There's a game plan out there that can work against NE; but it all has to go right.