Like NCFINFAN says, "Leadership. Tuna, Sparano, Penny, & Porter". I am going to agree but take it one step further.
Everyone here knows about the unreal turnaround. The darkest days coming after a loss to Arizona that gave the team an 0-2 record. Up next for the team in week three of the season was none other than the Patriots. Going back to 2007 the Dolphins had lost 19 of its past 20 games.
What Sparano was able to do, with the blessings of Parcells, was flip a switch (Wildcat offense) that probably sounded crazy at first. Nonetheless, the team bought into it --hook line and sinker! Yes, Porter and Penny had something to do with it. But the fact remains that Sparano was able to rally the troops in its darkest hour.
Getting a team to unify behind a single cause may sound a bit simplistic to some, but locker room chemistry is way underrated. When in Pittsburgh, Porter was seen as the locker room leader. He stirred things up. But the important thing about him was he always backed up what he spoke about.
The result was, in my opinion, the greatest case for locker room unification. aka chemistry ever seen in the NFL. Everyone here knows the rest of the story.
It says here that the Dolphins bought the system and therefore Sparano. This is the magic of sports in all its glory. Hollywood is probably looking into putting something together based on what happened.
But the most important thing that winning does for a team ,is, and RonBrown above said it best... It makes them "hungry for more"!