The twitter narrative (take it as you wish) seems to be that the "footy lads" were easily broken up into smaller groups gradually by the bobbies. By about 5pm (the curfew for these protests) some tube stations had been cordoned off (the live feed seems to confirm this to an extent, with footage of middle aged males shouting at police "where were you last week" and "we just want to go home"). At which point apparently roaming gangs managed to pick one or two of the footy geezers off.
This is a very general approximation of what I have seen from the various available sources. The tube station stuff seems to be correct though and would be logical as those locations can tend to be a flashpoint for pitched battles.
TBF this was a stupid idea to begin with, started by the usual bellends who either didnt turn up themselves ("Robinson") or no doubt left early on (Golding) and who will no doubt be looking to make money out of the outrage.
Everyone else turned up to a central London that has no open pubs, thousands of police already kitted up and in order to do something - protect the statues - from things that didn't happen last week anyway and wouldn't have happened this. They proceeded to make idiots of themselves, then after hours of rowing with the cops left themselves to walk around streets where everything is closed - apart from the supermarkets who weren't selling booze anyway - and where anyone who wanted to confront them could have stayed home, had their tea and then got to a safe spot and just wait for victims to walk by.
That some of them got beat up badly is horrible, for them and especially as the people who might justifiably have got a kicking had either not turned up or left in safe numbers by then.
WRT the tube station thing - the footage of individuals getting battered was at Trafalgar Square, Belvedere Road (by the steps that the Mandela bust is at the top of) and the approach to Waterloo itself; both Waterloo and Charing Cross have had some entrances closed all pandemic, so if these didn't know that they might have just assumed the station was closed. Not sure either was closed by cops, though its possible (edit: FWIW I can't see anything from TfL saying either was closed).
