One issue I am having with ten hag and united fans was the nature at which De Gea was pushed away, De Gea saved matches for United despite been old and not good with foot playing even when the team is performing bad last season. He was worth a season more to working side by side Onana until before the end of the season Onana would have been able to gather the confidence he needs to stop shots just like De gea.
While the did has already been done, Manchester United need to adapt to the system as it is by preventing blunder from occuring at the defense and making sure to score more goals than their opponent in every match so they don't get drawbacks from Onana's goals conceding in each game,
let's be realistic regarding these two goalkeepers. I don't think anyone doubts De Gea's ability to guard United's goal, even though his performance declined last season. now, the goalkeeper has been replaced by Onana. as we saw several times in the Premier League, especially in the Champions League yesterday, Onana made a blunder. However, it is also important to see that Onana often does his job of saving the goal quite well. It doesn't seem fair if we measure this goalkeeper in a short time.
Moreover, the League is not yet halfway through the season. Plus, United's back line players underperformed despite the injuries to the main players.
Suppose, United is still fronted by De Gea. that means, the situation is no better than before. The reason is, De Gea is more concerned with securing United's goal. but he did not contribute or help build the attack that started from him. In contrast, Onana is a modern goalkeeper who was involved when United started to build attacks. Onana's only weakness is from shots that aim upwards, it is not uncommon for Onana to always have difficulty in saving because his range is not like de Gea. But for De Gea, this is his specialty. So clearly, these two goalkeepers have different characteristics. IMO, if the problems in the United camp had been resolved including the return of injured players. Gradually, they will return to their best performance.