Tom Brady makes the the Dolphins offensive line better last year. Why? Because of his football IQ, and his ability to read defenses and digest information. It's a much higher level of quarterback play. Brady gets rid of the ball. And with Wallace, Hartline, and Clay, he would've had a much better set of pass catchers than he was working with last year.
You're flat out delusional if you think, all things equal, Brady doesn't squeeze out 11-5 out of the Dolphins last year. Tannehill and Brady aren't equals in any capacity.
(All according to PFF grading)
Would it surprise you to know that Tannehill performed better than Brady last season when pressured?
Would it surprise you that Tannehill was better than Brady when blitzed last season?
Would it surprise you that Tannehill was better than Brady last season on 2nd and long and 3rd and long?
Regarding your "gets rid of the ball" comment, you might want to check your facts.
Here are the percentage of times the two QBs got rid of the ball quickly:
0-2 seconds? Brady 32.6% of the time. Tannehill 31.8% of the time.
2.1-2.5 seconds? Brady 28.5%. Tannehill 28%
2.6-3.0 seconds? Brady 17.6%, Tannehill 15.3%