It looks like the ranking is based less upon the quality of the music from Set 1 song one to final night encore, and not even on only the best songs of the event, but rather the best moments of the jams of the event. A horrid 30 minute Wombat that ends with a great 5 minute peak would get ranked higher than a very good Divided Sky, Reba that was high energy but didn't go out on a complete tangent from the song. Other than the 4th set DQ which I don't grok, it's a consistent way of ranking, albeit somewhat non-standard.