Former Manchester United captain Bryan Robson believes ex-manager David Moyes dug a hole for himself by replacing Alex Ferguson's experienced backroom staff upon his arrival at Old Trafford in 2013.
As Sunderland boss Moyes prepares to return to Old Trafford for the first time since his sacking in April 2014, Robson questioned the Scotsman's decision to part with coaches Mike Phelan, Rene Meulensteen and Eric Steele just months after United won the Premier League title under Ferguson.
Moyes ultimately lasted less than a year into a six-year deal before he was replaced by Louis van Gaal and Robson feels the 53-year-old made life difficult for himself in Manchester ahead of the Boxing Day reunion.
"David was walking into the biggest job in the world and replacing the most successful manager in the world but he needed the right help," Robson told The Sun.
"I don't want to be seen as hammering David on his return but questions have to be asked about his time in charge.
"And, for me, the biggest one is why he got rid of the backroom staff and brought in his own men -- none of whom had won a thing as coaches.
"David made the decisions he thought were right. But staff members under Sir Alex -- they are your base. They knew the squad inside out. They understood the heartbeat of the club."
On claims Moyes was left with an aging and inferior squad, Robson added: "There wasn't that much wrong with the squad. They had just won the title by 11 points and I know Sir Alex was a genius but was he that much of one?
"Also, as I understand it, David had around £250million to spend that summer. So if there was that much wrong and you have all that money, why not spend it? He did buy Marouane Fellaini and then he got Juan Mata but, really, they did not have an impact.
"I get it that he was trying to do his best and the job he took on was gigantic but mistakes were made in my view and questions have to be asked."