Maybe the coach is doing some experiment to understand why many good players and even goalkeepers play well in other teams but when they arrive at Manchester United they play worse, but strangely when they leave Manchester United they play well again.
Manchester United has made terrible mistakes in the last 5 years

Fiorentina will trigger the option to extend David de Gea’s contract, confirmed.
“He will stay with us also next season”, president Rocco Commisso says.
https://x.com/FabrizioRomano/status/1910935918502174981At this point he would be playing for Manchester United and the team would have saved money, but they let him go and spent money to sign a goalkeeper who didn't have much experience in the Premier League. Honestly, I can't understand Manchester United's mistakes.
I don’t know if that is what Amorim is thinking but it wouldn’t be a strange question because football fans have been asking the same question ‘Why do good players become bad at Manchester United’?. Brining David De Gea back to the club will not solve Manchester United’s broader problems. I agree De Gea is a better goalkeeper than Andre Onana but it doesn’t guarantee that their performance is going to improve.