I witnessed that fighting on the Center between Punks and City fans, I was also present when all hell broke loose at the BQ club in st Pauls ( The Slits were playing ).
Incredibly exciting times to be a young lad, Great music, but it seemed as you have pointed out , that it was dogged with violence.
Mind you, It wasn't violent at punk gigs alone, I remember there was always a chance of violence just being in "Town" after dark.
It does seem safer nowadays, but that may be the mistaken perception of an old man.