Handing over the club to a new manager means placing more trust in the new manager than the previous manager and expecting the team to perform well under the new manager. Manchester United expected that and relied on Ten Hag but far from improving the team's performance this manager has consistently deteriorated under him.
All club management always places great trust in the Manager who has just been appointed as head coach, moreover, before selecting a Manager who is considered capable of improving the quality of the team, the Management first carries out a selection from several available Managers. Based on Manchester United's current performance, extending Ten Hag's contract is a big mistake made by the Management, they must be firm when it comes to work so they can immediately save the club from a deeper slump. Some Great Managers are still available right now, Zidane and Tuchel are experienced managers, I think if Manchester United Management chose one of those two names, maybe the situation would be different.
In the case of other clubs, if a new manager is appointed, if that manager does not perform well, then the manager is removed from the responsibility of the next season, but Manchester United did not do that, they only trusted this manager. Under this manager the team performed poorly for the entire season but they trusted this manager for one more season which resulted in this manager consistently making the team a bad team.
The case of dismissing a manager is nothing new in football, several great coaches have also experienced it, such as Jose Mourinho, Thomas Tuchel, Julian Nagelsmann and several other great coaches. Manchester United seem too cold with Ten Hag even though they know the team's performance is difficult to improve under his management. I am very skeptical about Ten Hag's ability this season, especially since the EPL is getting more competitive after Liverpool returned to their best form after appointing a new coach. Dark horse teams like Aston Villa, Brighton and Newcastle are also ready to provide a surprise, So Manchester United chances of finishing in the European zone at the end of the season are very small.