Ruben Amorim is an excellent coach. He was unable to improve Manchester United's position in the Premier League because the squad was too weak. The mistakes that Ten Hag made would not be resolved by simply changing the coach. It was necessary to correct everything from the entire squad to the new signings. There are players at Manchester United who are unable to perform well in the Premier League.
Now, for next season, we will see how both coaches will do, because Ruben Amorim has the chance to sign new players and sell the ones he thinks need to be sold. If he finishes in a bad position next season, then that is his fault. Regarding Ten Hag at Leverkusen, honestly, it is possible that even he will do very well, because the Bundesliga is similar to the Eredivisie.
Is Manchester United ready to do let go of the players that are not needed and replace them with new signing, if yes, then amorim can get it right, there are many outdated players in Manchester United squad which ordinarily are not supposed to be there again if not there's nothing amorim can do, there's no magic to this things, it is a practical something, I wouldn't want to mention Ten Hag because his refusal to listen to advise led to what manchester United is facing currently.
As for what to see from both managers in their different clubs side, Ten Hag may do well because the team he will be managing is already an organized team with good players but as for amorim, we already know what's at stake, he has one of the worst squad so far despite how he manage them, he will be needing good players to do the work with him, I just pity him because he came to the club when Ten Hag has already done somuch damages.