They opened with “Mr. Brightside” — they really opened with “Mr. Brightside.” And for those four minutes, with a festival throng rapt and shout-singing and chopping their arms in the air for emphasis, it looked like Brandon Flowers might’ve been right. Maybe the Killers really were the best band of the past 15 years. It’s a silly thought now, in the light of day, so many hours removed from the moment. But that moment … Brandon Flowers has a great solo album out now that he’ll be touring behind heavily until October, because of course he does. Onstage, his boyish charm radiates out to the far recesses of the crowd, and I swear his smile can melt ice. He’s not Bono or Springsteen up there, though he’s close. He’s fronting a band with some of the most explosive hits of this century, and they made sure to play them all — and a few Kings Of Leon covers as a nod to that band’s canceled Saturday set. They also rolled through a rollicking rendition of “Bad Moon Rising,” and it was in those moments, when they sideswiped expectations, that the Killers climbed as high as the stratosphere would let them. And then they waved and smiled at us from above, played “All These Things That I’ve Done” and “When You Were Young,” and called it a night.