Hughes was dismissed by City last night and replaced by Italian Roberto Mancini, the club's chairman Khaldoon al-Mubarak revealing the decision had been taken in response to a run of just two wins in 11 in the Barclays Premier League.
"I spoke to Mark last night and he found out immediately after the game when he was called into a meeting and informed that his contract was being terminated, but I think the decision had probably been taken some time ago," Bevan told BBC Radio 5 Live's Sportsweek programme.
"I think Mark and everybody else in this country realises that you can't buy trophies in one season.
"If they [overseas owners] feel that, then we'll continue with the sackings and we'll continue with affinity lost to our clubs in England, because I'm pretty sure the Manchester City fans will be sorry to see Mark go.
"If you come in as an overseas owner, you need to embrace the city, the supporters, not just the trophy cabinet."
Yesterday's 4-3 win over the Black Cats moved City into sixth place in the Premier League, a position in line with the board's pre-season expectations, and Bevan has accused the club's owners of shifting their expectations midway through the campaign.
"Mark is very realistic about the situation," Bevan said. "He knew the key goals he had to hit. His target actually was the top six. He was very disappointed because they were on target for that.
"For me, his reputation is still intact.
"Only two defeats - the fewest in the league - semi-finals of the Carling Cup, to me it looks like the goalposts were moved and the decision was made some time ago that he wasn't to continue in his role past today. I'm very disappointed for Mark and indeed the City fans.
"Mark would have delivered continued success without doubt if more time had been afforded to him and his staff, but he's left a platform for the next manager without doubt."