Also, coaching deserves a LOT of credit here. Gallant trusts all his players and allows them to make up for mistakes. Take Game 4 of Winnipeg vs. Vegas for example. Reilly Smith took a penalty and the Jets tied the game on the powerplay. Can you imagine what would happen if the Ducks were in that situation? Unless the player is named Getzlaf, Perry, Kesler (or any of Carlyle's other hand-picked favorites), they'd be benched the rest of the game. Instead, the very next shift Smith is out there and scoring to give Vegas the lead again. You don't see this happen on the Ducks because Carlyle doesn't freaking trust anyone.
I'm not wondering why a team like Vegas should be allowed to compete for a Stanley Cup in the first year. I'm looking at what the Ducks are doing wrong, and why they don't deserve to be where Vegas is. The fact that Carlyle is even coming back shows how out of touch this organization is with what it takes to win a championship. Those in charge of the Golden Knights aren't out of touch. That's the real difference. A lot of organizations think that they need established superstars to carry their team to a championship and rely on them, giving the rest of the roster minimal ice time. Vegas just selected a bunch of flat-out hard workers and understands that overworking your top line is going to do nothing but harm the team in the long run.
Edit: And one last thing. Fleury has been absolutely incredible. If you want to pick one reason that they're in the SCF that has nothing to do with management/coaching, that's it. The guy is just in another world right now. And sometimes that's the real difference when it comes to which teams make it to the final. How far would the 2003 Ducks have made it without Giguere playing out of his mind?