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.
Onana has made many mistakes, it cannot be denied even though overall Onana cannot be blamed for the poor performance of the Manchester United team, indeed overall the performance of the Manchester United team is not going well and the one who should be responsible is Ten Hag, he who has failed to develop the performance of the Manchester United team even though he has made many changes.
I think it is no longer suitable for Ten Hag's playing style to apply or indeed Ten Hag does not have good qualities as a coach to be able to improve the performance of the Manchester United team, so no matter how forced the results will still be the same and I think it won't be long before Ten Hag is fired.
Onana was actually a very talented goalkeeper when he was still playing for the Italian club, Inter Milan. But somehow when he was at Man United he became a goalkeeper who often made mistakes. So I once came to the conclusion that the real fault lay with the back line players who were too easily passed by the opponent which made Onana have to work harder. But after I tried to understand everything again, it seems like the problem is with the coach they have, namely Erik ten Hag. Although I'm not sure if after Ten hag is fired we will see a good replacement. but at least this must be tried if Ten Hag fails to take this team to a better path.
Man United maybe they will still be able to win against weak teams. but the problem is that they have lost twice against quite strong teams like Brighton and Liverpool. So I think this team is not so bad against weak teams but they are weak against strong teams. Which means that currently Man United is only a mid-strength team. they are no longer a strong team but also not a weak team.
With the manner at which Manchester united is being discussed lately, it shows that something is really wrong with them, or I will say the team are understand a semi crisis, because almost everywhere in the news, they are being mentioned, and it all boils down to their current form, so right now am just curious to know how would the hierarchy of Manchester united, I mean the Glaziers family to be precise, how or what would they be thinking right now? Are they really concerned on what the club has become? (a laughing stock) Or they practically don't care by turning blind eye to what has been happening without making a statement or they still believe in the ability of Eric Ten Hag?
I believe that time will tell if Manchester united can be able to continue like this or they are going to pull the plug, let's just watch and see where and when all these will eventually end.