These two points - that he has (1) preached a consistent vision to the team and recruits, and (2) learned from his mistakes and continues to improve - are what gives the most hope for sustained success and the most confidence in Sark. The guy is a great coach but is still learning and improving game to game and year to year. The fact that is smart enough to see problems and fix them, coupled with him being humble enough to understand he isn't perfect, is huge.
But the fact that he has an ethos, and that he both talks the talk and walks the walk according to that ethos, is probably even more important. You know he isn't full of bullshit when you see him take it on the chin after any loss and still refuses to throw anyone under the bus. When he puts in the players who give us the best chance of winning, regardless of what they think they deserve or have earned. When he is vulnerable with the team about his past and flaws, and encourages them to do the same with each other. He leads by example. Recruits and players are still kids and don't have the wisdom that you expect from adults, but they can smell bullshit. They know a fake. And they can see that Sark isn't fake.
Those aren't qualities that a person loses when the going gets tough. They take a lifetime to cultivate and become a cornerstone of who you are, and they are the foundation you lean on when shit hits the fan. I'm ready to say that Sark is the guy - and not just because he's winning games. It's how the team is winning games and how Sark is leading the team.