This is the perfect time for the Dolphins to address this position for the future. The idea that this team can win with a mediocre quarterback has been disproven, and an upgraded is needed. There are rumors going around about Miami being interested in signing Brian Griese, but even so, a quarterback needs to be taken in this draft. This is a very strong draft for quarterbacks, and there is a good possibility that Dave Ragone, Chris Simms, or Kyle Boller could be available to the Dolphins.
2. Left Tackle
The Dolphins currently have no left tackles under contract, so this is an apparent need. Mark Dixon is an unrestricted free agent that is talking about retiring. In the even he resigns, he will likely be moved back to guard anyway. This position will likely be addressed in free agency with Wayne Gandy being the top prospect. Miami may look to draft a project left tackle in the middle rounds like Seth Wand from NW Missouri State or Tim Provost from San Jose State.
3. Outside Linebacker
This position isn't a critical position for the defense. I'm fine with the current starters as they are, but the depth needs to be improved upon. A little competition for the starting position would never hurt. The Dolphins traditionally look for linebackers who have good coverage skills, are athletic, can run, and move well laterally. They may even look at an oversized safety as a linebacker prospect. Troy Polamalu is a safety that could get looked at as a linebacker by the Dolphins. Hank Milligan is another safety who has linebacker size. A player the Dolphins have taken an interest in is Lance Briggs from Arizona.
4. Wide Receiver
If the Dolphins can resign Oronde Gadsden, they are fine at the starting positions. Chris Chambers, James McKnight, and Oronde Gadsden are receivers that can make plays. The fourth WR position needs to be upgraded with someone that can return punts and kicks as well as play in spread sets. Dedric Ward was a disappointment, and Robert Baker failed to distinguish himself during the season. Look out for current Dolphin Robert Edwards's little brother, Terrence Edwards, with this pick.
I usually don't advocate drafting a punter, but with Mark Royals poor performance on the year, this may be a position that gets addressed in the draft. Royals gets really poor hang time on his kicks, and that allows opponents to get good returns on the Dolphins. He's a good directional punter, but the Dolphins need someone with more leg. Brooks Barnard could be an option late in the draft.