What's interesting is that the variable that's dragging down the Dolphins' season performance most is offensive net YPA, which is almost a standard deviation below the league average. When you multiply that with its corresponding coefficient, the largest one in the equation, you get nearly one loss on the year accounted for by offensive net YPA alone.
The variable most strongly responsible for the Dolphins' winning this year has been its penalty yards per play, which is nearly two standard deviations better than the league average. The defensive net YPA and defensive interception rate have been good, as well.
So essentially you have a team that's in playoff contention because it's well-disciplined, and because it has a good pass defense. Had those two variables not been what they've been, it's very likely that Ryan Tannehill's recent improvement wouldn't have been sufficient to get the team into playoff contention from the much poorer record it likely would've had.
In other words, the team's discipline and pass defense kept it afloat this year until Ryan Tannehill could improve sufficiently to get it over the hump and into playoff contention.
Last time I checked there were 11 starters on offense and half a dozen others who are asked to contribute regularly.