They didn't have much of a choice.

They initially had started selling tickets for their own concert at the same stadium, but tickets weren't selling well (GA Standing was $179, so is it any wonder?!).

So that Aerosmith gig was cancelled and they are now part of the festival.

The whole organisation of the festival has been a complete disaster - see the venue map and where the stage is.

They only announced it in February and so the stadium will be 75% unused.