Personally I think they improved more than we did. Not in a vacuum, but because they have an established QB. We gained playmakers, but are those playmakers going to get an opportunity to make plays? Swapping out Spiller for McCoy is a win on paper, but Spiller can be just as productive if given huge holes which McCoy has benefited from over the years (from what I've seen). Aging Incognito and rookie Miller are supposed to "fix" the line, but really the difference will be coaching, won't know if that's improved until the season starts. Meanwhile, Dolphins have a QB that has proven to be successful, but not great... good enough to get the ball into their new playmakers hands. Gained Suh and a stud rookie DT, so their line is going to be pretty scary.
I dunno... I just don't see myself sleeping on the Dolphins, they don't have the glaring question marks that we do.