I think it's self-evident that Pete Carroll does, in fact, do things significantly differently from most other head coaches.
I'm not saying that his shtick has never been tried before, but if you read his book you'll find evidence to support the notion that his philosophy drives his team-building and tactical approach to the game of football. That philosophy is pretty simple: don't try to make someone into something they aren't, simply maximize what they do well and figure out how to incorporate that into a coherent team.
People are always trying to do this, so it's not like the approach is what is different. It's his successful application of it that separates him from most other proponents of the philosophy. Like Beane in Oakland, Carroll is more interested in winning than he is in winning a certain (flashy) way. That's not to say he doesn't have his preferences as to how a football team should be built in order to Win Forever, since obviously he does (pound the rock, lock down the opponents' running game, and win the turnover battle).
So if you look at the proliferation of passing attacks in recent history, coupled with Carroll's eagerness to go to the UDFA/scrap heap scouring for talent, topped off with Seattle's consistent trading down in the draft (thereby reducing the amount of money they're required to spend on their roster), you see a guy who is standing in as stark contrast as is possible to the direction of today's NFL. The Player's Union won't like him (because of his shrewdness in roster construction), the league office won't like him (because he swims directly against the current of 'more passing! more passing!' mantra suffusing today's game), the other coaches won't like him (because he is able to do things they aren't)--the only people who will like him are the UDFA's and players who can't seem to find fits in other systems, and, of course, his own players who he actively works to ensure are as comfortable and game-ready as any coach they've ever played for.
He is absolutely a trend-setter, and his trend is one which runs diametrically oppsite the NFL's stated aims. His shtick is obviously not unique, but his success at the highest levels absolutely is.
And yeah, he's been caught with his hand in the cookie jar. But as the BoSox, Yankees, Bill Belichick, Lance Armstrong, Jon Jones, and just about everyone else who consistently wins at the highest levels would attest if forced to do so: if you ain't cheatin', you ain't tryin' hard enough.