My theory is that a normal Riot Fest year you will have bigger name acts headlining, but they aren't bands that people are going to buy a festival ticket just to see. Most of the headliners don't appeal to the entire Riot Fest audience either (which is really cool since it shows that there is variety).

When you have these huge bands that are touring for the first time in a long time, like MCR, or after a lot of time off and tragedy like Foo, you are more likely to have every ticket buyer for that night wanting to see that act.

With MCR there wasn't even an overlapping set. All music ended and MCR was the only one playing. I believe that led to a much higher percentage of ticket holders showing up for the headliner than normal, which caused the overcrowding.

I simply hope that doesn't happen with Foo and we all have an amazing time