No question, that's a factor. That's why the preseason always is a bad predictor. Sure, sometimes teams that struggle in the preseason sometimes also struggle in the regular season, and vice versa. But there's really no correlation.
As proof, just go check out Indy's preseason records over the past seven years when they've won at least 12 games every time.
Speaking of Nolan, is the early-season success on defense a credit to him and his approach/philosophy/schemes?
There most certainly is some of that as well, and we only have to go back to last year and see the work he did in Denver to realize that Nolan can make a big difference.
This year's defense, from what we know and have been told, is easy for the players to learn and tough for opponents to pick up on. That's a combination, and it can help certain thrive because they can just play instead of having to think too much.
Which brings us to the next question: Is it the improvement of certain players, the obvious example being Jason Allen?
He falls into that latter category, with Coach Tony Sparano mentioning more than once that Allen seems more comfortable now and less bogged down with the mental aspect of the game.
As a result, he's playing tremendous cornerback for the Dolphins. Yes, Jason Allen.
Is it the newcomers, with Karlos Dansby leading the way?
That's another factor. Dansby has been nothing short of awesome so far for the Dolphins and his biggest asset is his versatility. He can rush the passer (sack at Buffalo), he can stuff the run (fourth-down stop at Minnesota) and he covers like no linebacker we've seen in Miami in a long, long time (deflection in the end zone at Minnesota).
The Dolphins front office has taken some slack for its free agent misses in recent years, but this one most definitely looks like a big hit.
Is it a collection of young players emerging?
Davis, in fact, already looks like he could become one of the top cornerbacks in the league and Wake will reach double digits in sacks if he doesn't get hurt.
You look everywhere at this defense, and it's impossible to find a player who isn't off to a good start.
And here's the best part: The Dolphins have done this — holding Buffalo and Minnesota to 10 points apiece, on the road — without starting inside linebacker Channing Crowder, without projected starting strongside linebacker Ikaika Alama-Francis and with starting defensive end Jared Odrick missing the Vikings game.
One big question, of course, is: How long can the Dolphins keep this up? That, obviously, only time will tell.
As for our original question, we'll take the easy way out and just say the Dolphins defense has been so good early in the season because of all the reasons we mentioned.