Speaking on BBC's Planet Premier League program, the former England defender said: "We've lost so much identity over the years and it's been a process of slowly but surely we're just getting further away from where we need to be. We don't know which style they're gonna play, how they're going to play.
"It's going to be an absolute mammoth of a job. If you're the manager of Man United, you have to go in there and get the best out of those players. They might not be right away what you want, but, sort of deal with it and then maybe a year down the line we can assess that again."
He added: "I think we almost have to swallow our pride a little bit here. I know the way we want to play and the way that United fans expect us to play, but maybe we're going to have to play a certain way to build the confidence back up and bring confidence back into the team."