Sunday's 4-1 defeat at Manchester City has brought an even sharper focus on Moyes than already existed following his appointment as Ferguson's successor in the summer.
Various reasons have been put forward for the scale of United's defeat at the Etihad Stadium, which is terms of its one-sided nature had more in common with the 5-1 drubbing Ferguson's team sustained at City's hands in 1989 rather than the hiding suffered at Old Trafford two years ago, when the visitors scored three in stoppage time.
But it did seem to be the day when long-held reservations about United's squad were exposed.
And Moyes knows the six-year contract he was handed when he left Everton in May took that reshaping into account.
"I don't think it was ever going to be the case this was going to be easy and smooth after Sir Alex," said Moyes.
"There was always going to be days like this and there might well be more days like this.
"I hope not, but there will be because that is football.
"It was always going to be tough following such a great manager with a great team and I think people with real football knowledge will know there are probably some changes to be made.
"It is not going to be made in one fell swoop. It is going to be done in time.
"That is why the Manchester United board realised the job that needed to be done was a long-term one."
It was said to Moyes at various stages of the summer that nothing could quite prepare him for life at United.
That has been brought into sharp focus by the reaction to Sunday's defeat, that has swung sharply between understanding and sympathetic to outright hostility.
"I thought I was (prepared) but obviously when you come here then I realise maybe it wasn't," said Moyes.
"It is a club on its own. It is a fantastic place to work with great players.
"But we have to do well enough to make sure people on the outside think the work we are doing is the right stuff."
Moyes insists he is still enjoying the club and, bizarrely, victory over Liverpool in the Capital One Cup third round at Old Trafford tomorrow would mean he has enjoyed the best start to his tenure of any United manager since Sir Matt Busby.
Not that there was much consolation to be gained in such spurious facts in the immediate aftermath of the City debacle.
"Yeah, it did," said Moyes, when asked in the manner of defeat had shocked him.
"But when you're a football manager for the length of time I have been you are always going to have shocks."
Wayne Rooney has claimed Liverpool's arrival represents the ideal opportunity to bounce back.
There would have been plenty of interest in the fixture anyway given it marks Luis Suarez's return from a 10-match ban.
Suarez has history with United of course, famously snubbing Patrice Evra's offer of a handshake prior to the league fixture between the teams at Old Trafford in 2012 after he was found guilty of racially abusing the France defender.
Moyes accused Suarez of being a diver last season, triggering a swallow dive goal celebration in front of his dug-out when the Uruguayan found the net.
Interestingly though, there was a strong similarity between the way United and Liverpool dealt with Wayne Rooney and Suarez in their summer contract stand-offs.
And Moyes' words ahead of the fixture were of the conciliatory variety.
"He is a talented footballer," said the United boss.
"He is a very good striker and we will need to be on our guard against him.
"He has been good for Liverpool. Hopefully he is not too good tomorrow."
Changes are anticipated for United, although Robin van Persie is still missing with a groin injury.
Ten members of Moyes' squad have not amassed more than 90 minutes' action this season, including Nani, Javier Hernandez, Rafael and Wilfried Zaha. Jonny Evans and Anders Lindegaard have not been introduced at any stage.
Moyes is making no promises about their involvement.
"I will get to see them all play but that could be in reserve games, practice matches or the first team," he said.