However, talkSPORT understands the Premier League giants now acknowledge it was their fault the current West Ham manager wasn't a success at Old Trafford.
This is one of the many shock revelations to emerge following news of Ed Woodward's imminent departure as executive vice-chairman at Old Trafford.
The Red Devils struggled on the pitch in their first season following the departure of legendary boss Ferguson.
And it appears there were as many issues off the pitch as there were on it, with 'power struggles' between managers and the recruitment department seeing big Man United signings fail to come off.
talkSPORT host Jim White revealed in his first summer at Old Trafford, Moyes vetoed a move for a then 22-year-old Barcelona midfielder Thiago, who ended up moving to Bayern Munich.
The Red Devils then forked out just shy of £30million to bring in Fellaini - the Belgium following Moyes to Old Trafford from Everton.
Well, we know how that ended. While he did have his moments, Fellaini is widely considered a flop at United despite lifting the FA Cup, Carabao Cup and Europa League under Mourinho.
Thiago, a four-time LaLiga champion with Barcelona, moved to Germany and went on to win a stunning seven consecutive Bundesliga titles with Bayern, plus the Champions League crown, and now plays for arch rivals Liverpool.
"It's our understanding that in the early years, post-Sir Alex, part of the issues with recruitment at United was down to veto power struggles between managers and the recruitment department," said the White and Jordan host.
"Let me give you two examples. Under David Moyes, the recruitment department lined up Thiago Alcantara, now of Liverpool.
"But the club ended up with Marouane Fellaini due to the manager's veto."
White added that Jose Mourinho, who is understood to have turned down the chance to re-sign Cristiano Ronaldo in 2018, encountered a similar problem when trying to push the club to sign a defender that summer, but was told 'no' to his No.1 target.
It is believed the correct procedures are in place now but, according to a club source, more could've been done to help Moyes be a success at Man United.
"Sources inside the football club have told me that they didn't give Moyes the right structure to be successful," said White.
"They believe it was their fault and not his.
"They believe it was the wrong time for Moyes to come to the football club. All these years later they're saying it was them who let Moyes down, and not Moyes letting United down."
But Simon Jordan believes the Fellaini signing shows that the Scot didn't always help himself.
"If you compare Moyes with other managers then that argument holds water," said the former Crystal Palace owner.
"Did they let him down on recruitment? Well, if they offered him Thiago and he chose Fellaini, then you've got to ask who let who down.
"Where they did let him down… you don't run a business based on what the media tell you, you run a business on the back of what you see and what you know to be the case and what you believe are the reasons why you employed somebody. When you fire somebody, there's no winner, everyone fails.
"David Moyes walked into a nigh on impossible situation because it's universally accepted that the squad that won the title in 2013 were in the knackers yard and there was a need to rebuild the team.
"And the oracle Sir Alex Ferguson worked and it was unbelievable to get them to win the title.
"They bottled it. The guy wasn't particularly doing anything wrong but there was always going to be a backlash because he wasn't Sir Alex Ferguson.
"David Moyes can feel let down, but I don't think he helped himself either."