For the sake of being competitive, they may have to sign at least one impact free agent on defense. Granted, it's not going to help an already dangerous cap situation, but it seems like at this point you either blow things up and start over or you ride it until the wheels fall off.
I mean, honestly, what do you do if Hatcher walks? Are you going to roll out a 2014 defense that features Nick Hayden and Drake Nevis as your starting DTs? Maybe the team will fall into a random stroke of luck with a player like Henry Melton -- coming off of ACL surgery, familiar with Marinelli -- those are the types of factors that can lead to free agency "discounts," if you're able to strike up a deal right out of the gate before no other team has a chance to jump in. Then you're one first day draft pick away from a front four that would look like:
DE: Selvie/Crawford rotation (unless Crawford lives up to his pre-draft hype as a potentially solid starting strongside DE and wins the job outright)
DT: high draft pick
DT: Melton
DE: Ware (hopefully at a paycut, because he's too brittle to restructure at this point)
I mean, that's nothing to get too excited over, but it has the potential to be solid, especially given the right coaching. I have to imagine they could still decide to slot Crawford as a DT if a stud DE fell to them in the draft.
Long story short, I think the plan to fix the DL will very much resemble the approach this season to fix the OL. Very methodical, with no wholesale changes. A high draft pick here, a solid free agent there, and then try to fill in the gaps by developing the depth you have. Of course, the OL is still a work in progress, but they're probably scouting OGs pretty heavily this draft with Leary's knee being a potential ticking time bomb and Berny being... well, Berny.