The Dutch coach, Erik ten Hag, has come under fire at from Old Trafford fans for his side's underwhelming performances this season.
Calls for his head grew louder following the one-sided 3-0 defeat by Tottenham Hotspur last weekend.
McCarthy was let go by the Red Devils following the expiry of his contract at the end of last season, with former club legend Ruud van Nistelrooy appointed.
Now when asked what he feels the problems at the Premier League club are, the former Cape Town City and AmaZulu coach slammed Ten Hag’s lack of fight.
United are next in action in the Europa League against Porto on Thursday.
Ahead of the game, McCarthy said in the Athletic: “In modern football, I believe that players want to see a bit more passion in their coach.
“They need to feel that the coach is with them and willing to fight alongside them.
“Tactically, I feel that Erik is at the top. He lacks a bit of that fire, that passion. That’s where we differ, him and I.”
