The problem is that every mistake made by a player is not the best evaluation by Ten Hak because he trusts some players too much. I want to highlight how Onana often makes blunders but he is always the goalkeeper who is trusted by Ten Hak. Even though he still has alternatives to replace so that Onana can learn not to make mistakes and if he makes a mistake then the stakes are that he will lose his place as the main goalkeeper. Ten Hak must dare to make decisions and players who often make mistakes must be benched so that they learn not to make mistakes. The performance of midfielders like Bruno is also not good and sometimes he is too selfish so that a warning is needed from the coach and vice versa for the front line which needs to be given opportunities to other players.
From the selection of players we can judge that Ten Hag is quite selfish, he always trusts the players he chooses even though the players often make mistakes like Onana who often makes mistakes, even that has happened since last season but because of Ten Hag's selfishness Onana is irreplaceable.
Even Ten Hag's character is the same, he has had a feud with several Manchester United players which ultimately the players could not contribute to the Manchester United team, I think the problem is Ten Hag's selfishness, that's what makes everything worse.
Now there is nothing to expect from Ten Hag anymore, Manchester United has not shown an increase in performance this season which means Ten Hag has failed again, and I hope Manchester United management can make a firm decision for the progress of the team in the future.
Though I agreed that with your opinion on Onana being prone to mistake, however I still rate him as a good goalkeeper and I believe Erik ten Hag had sticked to playing him as their main goalkeeper because of his ability to use both feet which he can use to launch a counterattack or to start build up play from the back, those are two qualities abilities he had in his possession which I doubted any of Man Utd reserve goalkeepers has those qualities, these are tactic adopted by Man City goalkeeper Ederson and Arsenal Raya which had helped the team to become very competitive thus Onana needed to up his game in term of correcting his mistakes.