My brother used to go to things like the WTO protests.  He pointed out that antifa, the current incarnation of the anarchists that have been violent at protests for years, have learned how to fight a very organized opponent (the police).  The white supremacists, while they think they know what they are doing, were just outclassed by folks who have been doing this crap for years.  It comes back to the Mike Tyson line, "everybody has a plan until they get punched in the nose".  The anarchists know what they are doing when it comes to street fights, the white supremacists don't.