The talent is there for this unit to be a strong one. Of the three safeties and three corner backs who receive most of the playing time, there are three first round picks and three second round picks. The problem with this unit has been health and consistency.
Corey Webster has developed into an excellent starting cornerback, and although he is not the elite corner he recently claimed he is, he is probably top-15 at his position. Aaron Ross will never live up to his rookie season, but he has the ability to be a competent number two corner back, even if he is the most maddeningly inconsistent member of this defense. Had Prince Amukamara not lost so much of his rookie season due to injury, he may have wrestled away Ross' starting spot by now.
Kenny Phillips may never regain his pre-knee injury speed, but he and the outspoken Antrel Rolle form a solid safety duo. Deon Grant has clearly lost a step from last season, but he still plays the run well and has looked much better over his past few games. Like the corners, these safeties have shown flashes of brilliance, but struggle to perform that way consistently.
No unit has been as lousy, statistically speaking, as the Patriots' secondary. It's gotten so bad for this group, which ranks second worst against the pass in all of football, that they had to convert slot receiver Julian Edelman into a defensive back to give the struggling secondary another warm body.
It has undeniably been a tough year, but there are some bright spots. Cornerback (and local Hofstra product) Kyle Arrington tied for the league lead with seven interceptions. Other bright spots include...umm...I guess Sterling Moore isn't terrible...Patrick Chung and Devin McCourty used to be pretty good...James Ihedigbo is a pretty cool name...
The Patriots' secondary has played much better during the playoffs, and the extra week should give Bill Belichick a chance to figure out a scheme that will protect against the defense's biggest weakness. They'll never be great, but if they are even just competent, it will give this team a huge boost.
Neither of these units are a strength, and at times, they can both look like the worst secondary in football. Luckily for the Giants, a recent switch to a less complicated man-to-man system has allowed for improved play. New England's secondary has also been better recently, but that is partially due to the fact that they faced Tim Tebow. Both of these secondaries have a tough task ahead of them, and it's unlikely that either one will get the best of their battle with the opposing offense's receivers.
I give the edge to the Giants, but that's more due to the Patriots' shortcomings than anything else.