If they were dead set on drafting a DT then I guess they got the best DT they could get there. Obviously hindsight is 20/20 but I wouldn't think Bill would ever go into a draft saying "we need to draft X position at 32. He hasn't been terrible as he has started many games but he hasn't been good. They seem to try and replace him as a starter (or at least get someone to take some snaps from him) quite a bit by signing Branch and trading for Shelton. He was billed coming in as someone who could play both nose and traditional D-tackle and maybe he can just not too well.
Their position of greatest need at that time was DT, particularly after the Easley bust. When you've got such a solid and good roster - one that gets you deep into the playoffs each year, well...BB's philosophy seems to be "who can make the team?" whether it's through special teams, like Cardona, or to serve as the backup - Brisset and Jimmy G - he's filling very few holes in his roster by draft time, and very few he wants to fill with a rookie.
The problem right now is that all of the Pats leaders - Hightower, Chung, McCourty(s) on D, Brady, Jules and Gronk on O - are getting old. A healthy Bentley (and hopefully Sam) will help at LB, but I wouldn't be surprised to see the Pats go there again in the draft. Van Noy, traded for a mid-round pick, has become pretty damned good, too.
Obviously, and particularly if they lose Flowers, they're going heavy changes on the D-line this year. They'll probably need to find two.
They need a #1 WR. Maybe it's a guy on the PS now, maybe someone they bring in through FA (doubt it'll be a draft pick). Still, Brady's had a bad year and Gronk had has a really bad year, and yet, look, they're 8th in the league in scoring.
If I had to guess why they look so vulnerable this year, I'd put it mostly on Brady - the eye test tells me he's bailing early on plays, missing wide open receivers (Hogan, repeatedly) and throwing off his back foot a lot. A few times, it's looked to me like he's trying to not get hurt, which makes me believe that he is (knee). He really turned downward after that knee brace incident in Miami.
Still, except for 7 seconds in that Miami game, they'd be playing as huge favorites for the #1 seed, and if Pitt and the Titans don't make the playoffs (and I don't think they will), they've beaten every playoff team they've faced.