Former Manchester United defender Paul Parker believes Memphis Depay and Anthony Martial are unhappy under Louis van Gaal due to the Dutchman's strict management style.
Van Gaal guided United to fourth place in the Premier League table last term, while they sit third in the table this campaign, trailing leaders Manchester City by just one point.
The Old Trafford side have received plenty of criticism, though, and Parker has blamed Van Gaal's lack of flexibility for his attacker's underwhelming form.
"Sir Alex Ferguson knew how to manage his players. As his side changed, he too had to alter his management style," Parker wrote for Eurosport.
"He did - and that's why he was able to drag Manchester United to the Premier League title in 2013. Did he enjoy it? No. But he did it anyway.
"When Louis van Gaal arrived at United, I thought he too would be flexible. But we now have a situation where there are a lot of discontented players and we have to question why they are playing badly.
"I look at Martial and worry for him. He looks like a boy who doesn't smile anymore. He doesn't look like he's enjoying himself.
"The form Depay is showing hasn't just happened because he's playing in the Premier League. That boy probably feels like a scapegoat. He's in a country relatively close to where he's from, but feeling a million miles away."
Parker then went on to stress that Van Gaal is not getting the best out of his players due to his poor man-management.
"Van Gaal puts the fear of God into players," the former England man added.
"It has to be his way. He selfishly manages the team. And no one enjoys it. He may be a successful manager, but he must learn - even at his age - to become a good man-manager.
"At the moment we have to say he's not man-managing that team. All those players he's got are not bad players, and they've not played negative football all their lives.
"He's being incredibly stubborn. Any player who doesn't conform to what he wants is chopped. He looks for a player who's made a mistake, then drops them for the next game."