No one doubts that Andre Onana is a good goalkeeper. His career shows it. But what worries me is that the Manchester United defense makes very simple mistakes. Andre Onana can react harshly to simple mistakes made by the defense. After all, someone has to react that way anyway. You cannot expect high performance from your goalkeeper when the defender makes too many mistakes.
If you want to get a high performance out of Andre Onana, the technical team should make the defenders more careful or sign new players.
Andre Onana will not be able to withstand attacks from the enemy against Manchester United alone. Teamwork with defenders is very important for Andre Onana. Andre Onana must stay focused as a goalkeeper and turn the mistakes he has made into very important lessons so they don't happen again in the future.