Irwin believes that Louis van Gaal can turn things round and improve upon David Moyes' traumatic season, in which United slumped to a 7th placed finish.
"We've had 23 years of success, we need a little bit of patience," Irwin told the Daily Mail. "You should not forget that we had years within that when we didn't win anything. Before the Swansea game, you could feel the optimism around the club.
"It wasn't a great performance and it was a poor result but hopefully, moving forward we can forget about that. We had a real poor year by our standards last season and I've no doubt that we will be an awful lot better this year.
"I think we have a manager who has a fantastic record of success of not only bringing players in but also using young players. He has managed some of the top clubs in the world - Barcelona, Bayern, Holland at the World Cup - he did great things with AZ a few years ago as well."
For the big stories and the banter follow us on Twitter: @tribalfootball