The secondary indeed at times played like at elite level, and was probably one of the stronger units in the AFC, something that I predicted would happen a year and half ago when the secondary was in shambles and I suggested trading for Aqib Talib and moving Devin McCourty to FS:
http://www.patsfans.com/new-england...ass-defense-about-go-terrible-very-good.html
Aqib Talib played at a near-MVP level the first 6 games of the season before getting dinged, and Devin McCourty was the best safety we've had since Rodney retired. He's not at the Earl Thomas level yet, and calling him a "top 2 FS" may be a stretch, but he's still learning the position. Alfonzo Dennard is an above average #2. Kyle Arrington was up and down - he's a mess outside, but at times very good in the slot. Injuries may have played a factor. Logan Ryan and Duron Harmon had promising rookie seasons, and provide solid depth. I'm optimistic about the secondary, and that improvement is one of the reasons that I really want to maintain continuity and see Aqib Talib re-signed.
However, the secondary was too inconsistent and too porous on 3rd down to really call it an "elite unit" for 2013. It had flashes, but also major gaps. And the loss of Talib had a major impact on the overall level of secondary play.
IMO, there are 2 areas in the secondary that need to be addressed, aside from the obvious re-signing of Talib or finding a replacement (again, something that I really don't want to do):
1. Get depth at outside CB, particularly big, physical CBs who can play press man. I NEVER, EVER want to see Kyle Arrington outside, under any circumstances, much less STers like Marquice Cole. Unacceptable, especially when you can get big, physical CBs who can play press-man on day 3 of the draft.
2. Upgrade the SS position opposite McCourty. As Ashley1992 points out, while Gregory wasn't awful, he was the "weak link" in the starting secondary (aside from the times when Arrington was played at outside CB), and far too often failed to police the middle of the field. He's a good backup/rotational player, but over-priced at a $3.5M cap hit; and an upgrade is certainly desirable. We can debate the relative priority of that desire, but arguably a physical SS with coverage ability who can make opposing receivers pay and make them think twice about going over the middle would help a lot.
I agree that the DL is a high priority, and would make the secondary better, and I've repeatedly called for that to be an off-season priority. I certainly think we need a rotational DE, a pass-rushing DT (though Kelly, Jones and hopefully Armstead provide a fair amount of ability and depth at that role), and also quite possibly (probably, IMO) a replacement for Wilfork if he is unable to recover from his injury to an adequate level in a timely fashion. There is obviously synergy - better DL play makes the secondary job easier, and better secondary play buys more time for the DL to get to the QB. I don't see why both areas should't be potential targets for improvement, depending on how things fall.