The injury will be helpful for Onana to have a rest and time to find a psychology balance that is very necessary for him and his career in Manchester United. He has been playing under a lot of pressure and eyes that seem to take him down whenever he makes mistakes and give them chances to attack. Without an injury, it's hard for Onana to have a necessary break time as Ten Hag still considers Onana as a best goalkeeper in Manchester United.
There is rumor that Manchester United and Ten Hag want to bring David De Gea back in the winter transfer season at least with a short term contract. The injury of Onana when it's about one month till the open time of transfer market will give them more reasons to think about this idea more carefully and seriously.
Where is the shame With Ten Hag? This can only be rumors because De Gea is into something bigger right now. The last time is heard about him was he was trying to buy one club together with Atletico Madrid ex goal keeper and it's even more certain of him to return to Real Betis than Manchester united that couldn't extend his stay in the club.
It's even better for Onana to have some break, he has been stressed out emotional and physically because he is tte only man behind Manchester united matches throughout the season. They should locate Spain, they will definitely get new players for the club than recycle old players over and over.
Is not the end of the world for Manchester United and don't say it like Onana is the only goalkeeper they have in that team. I believe with him being out of action it would give him (Onana) time to rest and it will reduce the amount of pressure on him. The second choice could cover for Onana and even do better, these days goalkeepers are the ones who look for opportunity to showcase themselves just to be in the first team.
Playing under huge pressure and after having bad start is not easy for all player. Pressure is very harmful for player performance and if they fail to be strong against pressure, their performances will be affected negatively. We saw it with Morata, Lukaku in Chelsea as without confidence, a player will play worse than what he can do with his best. Therefore, a few weeks to sit back and take a break, avoid more pressure whilst have time to analyze past mistakes will help Onana to improve a lot when he returns.
Pressure is not good in any match's but Manchester united always using that as excuse because they are used to it, they conceded goals like a baby team. They don't stabilize their games and return the same pressure anytime they are surrounded by pressures from opposing. Score 1 goals and then conceded 3 goals without even feeling anything. That hurt even even when the players doesn't feel like the fans feel devastated in every game they lost.