There were more factors to that (fans complaining about crowd misbehaviour on Twitter, band not really "on fire"). But of course nothing tops being there. And even being there, and even being in GA, it can be radically different if you're surrounded by a nice crowd or a bunch of jerks!
You know what would be a fun way for U2 to screw with people? Do that long intro to One, and then.... the bass picks up and Edge just rips open and BAM it's Mofo