There's no reason that Miami can't make it back-to-back playoff trips. I'm going to be optimistic and say 11-5 and a wildcard. New England probably goes 14-2 so catching them likely won't happen this year.
The big thing for the Dolphins is they know who they are. They have an identity. It took the team until game six last year to find that. Miami is going to pound the rock with Jay Ajayi and if teams commit eight players to slow that down, the Dolphins have the talent in the passing game to go that direction.
I believe the defense will be better. I'm concerned about the wide 9, but I wouldn't be surprised to see that modified a bit and maybe used mostly on passing downs.
The play of the linebackers against the run should be much better with Timmons and McMillan added. There's more depth and talent on the defensive line, though I am concerned with defensive tackle opposite of N. Suh. Jones is back in the secondary and there's some talented young corner who could take that next step.
This should be a good year for the team with maybe one playoff win.