Edge Rusher
The Dolphins whether through the draft or free agency need to find pass-rushing defensive ends that can put pressure on opposing quarterbacks. It was one of the worst positions on the field last year and the depth is horrendous.
Brian Flores likes to use his linebackers to blitz the quarterback and that is all well and good but edge defenders also maintain the outside against the run and last year the Dolphins struggled. No one currently on the roster is a viable starter out of the gate so finding more than one is important moving forward.
Quarterback
You may disagree but QB is not the biggest off-season priority. At worst, the Dolphins go into the season with Ryan Fitzpatrick and Josh Rosen and maybe Rosen gets more reps and more of a chance to prove he can lead the team into the future.
The Dolphins are not expected to sign a free agent QB but as we know that can always change and if they view another veteran to be a better option than one of the two on the roster, they will make that move. As for the Draft, well the Dolphins are one of a handful of teams expected to draft a QB and draft one early at that.