United's form has taken a drastic upturn since the restart, which McAteer believes can be attributed to Fernandes' arrival.
"Manchester United were in disarray not long ago," he told Racing Post. "There seemed to be a lack of characters in the dressing room but the lockdown now looks to have provided them with a welcome break and they have benefited from some work on the training ground.
"They have started back well and Bruno Fernandes has been brilliant.
"He has made Paul Pogba look a better player and you can tell the younger members of the team have been given more confidence.
He added: "Much of their rejuvenation is down to their Portuguese midfielder."