The thing is most people aren't trained fighters. This is a trained dude kicking the ass of some shmucks who can't even throw a punch correctly. If they can't punch I doubt they're going to be able to practice any kind of unit tactics, even the basics.

That said, the boxer did a lot of work to make sure he wasn't surrounded. Later in the gif one guy rushes him to try to take his right side and the boxer stopped retreating to knock him the fuck out. He also changed his footwork to make sure he keeps his enemies in as much of a line as possible. Someone gets out of line within striking distance and he knock them out first. You can also see how he keeps the crowd and cars to his left, so that you simply can't flank him on that side.

You can also see one crowd member pulling on the shirt of one of the Boxer's enemies. The dude was rushing hard and might indeed have gottem the boxer tangled up. I just re-watched and you can notice the crowd actually goes out of their way to slow down the noobs as they do try to rush the Boxer. They simply couldn't because 3-4 citizens hold them back, giving the Boxer the space he needed to basically kite the rest.

If this was some random dude he would have gotten owned hard. But the single dude in this video was just beyond their level.

TL;DR- I agree the aggressors here sucked, but we also need to appreciate the training and ability of the dude who used his superior knowledge and physical prowess to make a huge group of dude look like toddlers.