Moyes, 60, succeeded legendary Red Devils boss Sir Alex Ferguson in 2013 after the Scot’s 27-year stint at Old Trafford.
But in April 2014, after just 10 months in the job, the ex-Everton head coach was dismissed with Man Utd languishing in seventh in the Premier League table.
He won just 27 of his 51 games at the helm, before Louis van Gaal came him in as his permanent replacement in the summer.
Six-time Premier League winner Ferdinand, 45, who spent more than a decade under Ferguson, has now detailed what the issues were following Moyes’ arrival.
And he pinpointed his philosophy in training – an approach more focused on the opposition – as a major sticking point.
Speaking on the Obi One podcast, he said: “As a professional I wanted him [Moyes] to do well and you’re giving them that time and the chance, definitely. But there’s a few things you see that aren’t the same.
“I think the biggest thing for me was that there was always too much focus on our opponents in training. We’re Man Utd, they’re meant to worry about us more.
“What that does to our mindset is there’s an element of fear here and that filters through to the team and to the young players.
“All we’re doing is talking about what are they going to do, but it should be about what are we going to do?
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‘That element there, I thought there needed to be a bigger shift from thinking like an Everton manager to thinking like a Man Utd manager.
“It needed to be how champions think.”
Yet despite Moyes’ shortcomings as Man Utd manager, Ferdinand insisted he has sympathy for him.
He added: “But I do actually still feel sorry for David Moyes because of the shoes he had to fill, coming to Man Utd from Everton is a completely different ball game.
“Even Mourinho may have struggled coming in after Sir Alex, so to think it was an easy run for Moyes was crazy.”
After being sacked by Man Utd, Moyes endured difficult spells with Sunderland and Real Sociedad.
But since beginning his second stint at West Ham in 2019, he has enjoyed great success in the capital.
After guiding the East London outfit to sixth and seventh place finishes, he led them to Europa Conference League glory last season.
And they are continuing to look strong in the current campaign, sitting sixth in the Premier League having safely booked their spot in the last 16 of the Europa League.
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