My Live Sound teacher worked for Splendour in the Grass this year, apparently the Yeasayers didn't contact Splendour at all about what kind of instruments they'll be playing, the mixing order preference of their engineer etc. etc.
My teacher had to look for the band themselves, and came across one of the members (I think his name was Mike or Mark), drunk at the pub, and got the most dodgiest patch list he's ever seen.
(but tbh the guy is a musician, not a mixing engineer. It should be noted that my Live Sound teacher is Irish. Very Irish.)
So this year they apparently played without an engineer to properly mix them, all their channels were set at Unity. No EQs, no compression, fx or nothing.
EDIT: Never listened to Yeasayers, btw. I just laughed when on the Patch List, there was a big "**** KNOWS" next to Yeasayer's timeslot.