That's according to Louis Saha, who is concerned about apathy in the club fanbase after a poor start to the season.
United sit eighth in the Premier League after five defeats in 10 games - the latest being a home humbling at the hands of rivals Manchester City - and face an uphill battle to qualify for the Champions League knockout stages after two defeats in three group games.
Ten Hag has approached the job at United with a no-nonsense style, bombing Cristiano Ronaldo out of the side a year ago following public criticisms and now ostracising Jadon Sancho after the winger spoke out. But there are now reports such a hardline manner is affecting squad harmony.
Ten Hag needs to be bold but sometimes recognise his own mistakes and admit to them.
Saha believes the manager must continue to be bold in his decisions, both behind the scenes and tactically before and during games, but feels results have affected both the squad and the supporters.
“There is definitely a sense that the fans are losing belief at United," he told BettingOdds.
"The fans expect you to show fight and they need to see you challenge in games like this. We didn’t see the energy or the aggression required to compete in a derby game and they lacked spirit. That falls on the manager and the fans made sure that was understood.
"The players need to understand it’s not good enough. Ten Hag needs to be bold but sometimes recognise his own mistakes and admit to them. His decisions have an impact and he got some wrong against City and he should be criticised for that."
Sancho continues to be excluded from the group and now trains with the youth team, even reportedly banned from dining with the first-team squad.
Saha feels Ten Hag has gone too far with his punishment of Sancho and let his ego take over.
He added: "The Sancho situation could have been handled better for sure. Of course, Sancho has responsibility but the manager does too and he needs to help him. Everyone is losing in this current situation and Ten Hag has to put his ego aside now.
"This treatment is not right, it looks like the manager is trying to get revenge to show he has the power. If you want big stars playing for you at United, you have to help them express their personality. When they make mistakes, you have to give them a platform to say sorry instead of treating them so harshly.
"Jadon is a great player and of course, he has made mistakes and hasn’t performed, but now the manager has the responsibility to help him fix this."