I was there. And I can't help but be confused by the actions of the VSP and feel like the city kind of set everything up.
First they only had half the park closed off which caused the right to be packed against the barriers and allowed the left to pepper spray them, throw bottles and cans of cement, balloons of paint and piss, and using aerosol cans as flame throwers.
I watched as did the police as this went on for a hour and a half. There was only one entrance set up into the park and groups of 20-30 of the right would go out at a time to push the crowd back. Then it was declared a unlawful assembly and the right were pushed out of the park and into the crowd. It was crazy.
Again I think the VSP were just following orders from the city who should shoulder a lot of the blame.