I think there are two certainties about the Patriots heading into next season:
1) They really need to address almost every portion of the defense, from the d-line up to the secondary. Toward the end of the year last season, the Patriots did a fine job sort of mixing and matching guys to improve their horrid defense heading into the playoffs. The increased defensive efforts, I would say, were more from smart coaching than player talent. (That said, I did not watch every Patriots game. I only really caught their postseason games. If a Patriots fan takes umbrage with this claim, please call me out).
2) The Patriots have, like, 40 draft picks in the first two rounds - and by that, I mean 4. This seems like a pretty universal constant with the Pats, as does their ability to find good talent in the draft deep in rounds. I would imagine that at least half of these first four picks will be used on defensive players.
It simply is the biggest source of needs, especially since DE Mark Anderson left in Free Agency. One ought to expect lots o' pass rush to be flowing into New England very soon. This could (and should) happen on the levels of the d-line and the linebackers.
Moreover, the Patriots should try and find a dominant cornerback to throw in with the current crop. Again, toward the end of last year, the Patriots' secondary seemed to harden a bit. And when I say "harden" I mean the difference between pre- and post-refrigerated Jell-O. Getting a truly dominant shutdown type of guy would cover up some unfortunate pass defense blemishes.
Offensively, the team ain't nothing to sneeze at. The loss of RB BenJarvus Green-Ellis is a bummer. Maybe a later round RB will solve that problem. The Patriots also decided to collect all the WRs, what with the likes of Brandon Lloyd, Anthony Gonzalez, and Donte Stallworth.