Not necessarily in order of importance...
LT - Gross' deal expires and he may retire. Either way we need a new franchise LT for the future.
RT - Bell is garbage, need an upgrade here. Re-signing Gross and moving him to RT may be an option.
RG - No explanation needed. And I'm not even counting LG even though Silatolu will be coming off a major injury.
#2 TE - Need a legit threat to couple with Olsen. Having Shockey in 2011 made the offense much more dynamic.
#1 WR - Smitty is pretty much done, we need a big time playmaker to take over, a legit #1 receiver for the future.
#2 WR - LaFell is not the answer and he's a free agent anyway. Need someone that can consistently beat 1-on-1 coverage and take advantage of the easier matchups that the #2 receiver typically faces.
#3 WR - Ginn fits this role perfectly but he's a free agent. Re-signing him would be ideal.
RB - I'm listing this mainly because of the retarded contracts and injury history of both DWill and Stew. We may need to dump one (or both) of these guys and add some younger cheaper late round talent.
You could make a case for just about every player on offense needing to be upgraded except Kalil, Olsen, Cam and maybe Silatolu (IF he can return from injury). And of course there's people saying we should trade Cam and look for a new QB as well.
DE - Hardy is a free agent, that's a big hole to fill. Even if we promote Alexander to starter we'd then need to fill the rotational DE spot. All in all I hope we keep the Kraken around a bit longer.
CB - This has been discussed at length. Personally I think we have a solid group of mid-tier players, we only lack a true #1 CB that can handle the other teams top receiver. There's nobody currently on the roster who fits that description.
S - We have basically nobody here. Mikell and Mitchell are both free agents. Godfrey has one of those retarded Hurney contracts, his base salary explodes from 1.6 million to 5 million. Seeing as how he was never really good to begin with and he's been on IR all year I doubt he'll be back. That leaves us with only an UDFA in Lester and a couple guys that are just STers.
And of course... head coach, offensive coordinator, defensive coordinator, special teams coach and the whole list of assistants and positional coaches.
That's 8-9 starters, 3-4 more players that will be significant contributors, an entire coaching staff and I didn't even hit on the multiple positions that we need to desperately improve our depth.
We're also still operating with the same front office personnel, pro and college scouting departments that Hurney put together. We probably need to weed through that, cut some guys loose and bring in new guys there as well.
So.... good luck Gettleman. Get to work.