Speaking on his BBC Sport podcast, Rooney said: "I was watching it with Rio, Vidic, Maicon, Robert Pires, Gilberto Silva, Bastian Schweinsteiger, Ashley Cole and we’re all watching it and all struggling to answer how we see Man United play.
"If we sit down and watch United for a six-game period what the patterns are that we’re seeing that might improve the team going forward? All the players who I’ve just mentioned have played the game at the highest level and it’s very difficult to see that."
He added: "Me more than anyone else wants to see the club doing well. The difficult thing we have is we want to support the team and manager as best we can but we also have to be honest because the fans are not fools.
"City weren’t great. I think it was one of the worst Manchester derbies I’ve seen in a long time and City played their part in that too but still won 3-0. They’re finding their way and playing a bit of a different style.
"What’s important when you’re trying to implement a new style is win games while you do it but unfortunately for United and the manager it’s been not far off a year now and not far off less than a point a game. In a lot of Premier League seasons that’s relegation form."