Barton's future at QPR is in doubt after he elbowed Carlos Tevez, kicked Sergio Aguero and appeared to headbutt Vincent Kompany during the game and then took to Twitter to launch an expletive-ridden attack on Match of the Day duo Alan Shearer and Gary Lineker afterwards.
The Rangers skipper has until midday on Thursday to decide whether to appeal two charges of violent conduct, and the Professional Footballers' Association chief executive said: "If you come out with stuff like that you are going to deserve to be heavily sanctioned."
He added: "He is his own worst enemy when he says stuff like that and he has been upsetting a lot of people in the game with good reputations.
"We try to deal with Joey Barton and it is not getting any easier.
"I just feel sometimes like it is pushing a boulder up a hill, it slips back and you decide whether to go again.
"It has certainly been a backward step for him and his future in the game.
"There are people that seem to be improving and then slip back, it is a human condition. No one is perfect but you only have one career."
Source: PA
Source: PA