The former United boss has aired his views on why the former Everton star did not succeed in his debut campaign at Old Trafford.
Moyes signed Fellaini from Everton in a big-money move last term, although the Belgian did not produce his best for the Scot in a campaign that ultimately saw Moyes sacked.
But the 51-year-old admits Fellaini was only meant to be signed as part of a group of new recruits, meaning Man United's inability to sign anyone else ultimately cost the ex-Everton midfielder.
"Of course, he wasn’t meant to be our only signing at United that summer. He was brought in to compliment the squad and the other players we were hoping to bring in; to do a certain job in certain games," Moyes wrote in the Daily Mail.
"Unfortunately for Marouane, he was the only player we brought in and because of that he was seen as the big signing. It meant he was under more pressure than he perhaps should have been. And when the season didn’t start the way we all wanted it to, he came under a great deal of scrutiny, even if most of the attention was on me.
"I felt it was unfair that he was having to carry that extra pressure and expectation, and deal with extra criticism, simply because David Moyes had signed him.
"I think he’d be the first to admit he maybe didn’t always play as well as he could have done when he got the chance."