Former Manchester United assistant manager Carlos Queiroz has accused the club of "panic buying" and said there is a lack of star quality at Old Trafford.
Queiroz, who had two spells as assistant to Sir Alex Ferguson, said he believed both David Moyes and current manager Louis van Gaal had made mistakes as United adapted to life without their most successful-ever boss.
A summer of heavy spending by United has given them the third most expensive squad in Europe, and Queiroz told the Guardian: "A club like Manchester, with its financial capabilities, the results must be there immediately.
"But we also want to see the players shining. Great players like [George] Best, [Paul] Scholes, [Ryan] Giggs, [Roy] Keane, [Ruud] Van Nistelrooy -- where are they? Where are the stars of Manchester United?
"It was always about creating players. Now it is the opposite. And even some of the players that arrived in the team like [Radamel] Falcao and [Angel] Di Maria were on the bench. I saw Di Maria in some games, and he looked like he has never played football.
"There is panic buying. You have to prepare and then make the decisions together. You can still make wrong decisions, but we never made panic decisions when buying players."
Queiroz stressed that he had "great respect" for both Moyes and Van Gaal, but said "crucial and critical" mistakes had been made at Old Trafford since Ferguson's departure.
"It was not necessary to turn everything upside down with the staff, with people like [former assistant] Mike Phelan, people that know the inside of the club," he said.
"I learned with people like Bobby Charlton and Alex this magnificent lesson that you must trust your own people. There are no other people in a better position than your own people to know what to do.
"No other people could be better prepared to make the right decisions in terms of continuity... we need to see some leadership."
He said he hoped that United, who have finished seventh and fourth in the Premier League in the last two seasons, would be "able to not only compete, to win but to win in style because that is what Manchester United is about -- winning with style and entertainment."