In as much as Erik Ten Hang didn't have a nice season, it doesn't make coaches like Xavi Hernandez and Thomas Tuchel better than him. If I am among Manchester United management, I cannot any of the above coaches above Erik Ten Hang.
Certainly, it seems Manchester United is not interested in dismissing their current coach. They might have concluded to give him one more season and make available players for him to try again this season. I personally believe that Erik would have done better if there were available players for him throughout the season. For the majority of the season he played without good defense, to the extent that Casemiro was occasionally made to play defense.
As you said, they should be in the top position, but currently Manchester United is not in their best form. The coach is still having difficulty finding a good strategy to win every match. It is possible that the coach already has many names of players he wants to buy, but it is possible that Manchester United management will not provide support to Erik ten Hag. This means he is having difficulty maximizing the strengths of the players he has. Erik ten Hag must make good use of this one season opportunity at Manchester United to show that Erik ten Hag's strategy still has the potential to bring Manchester United to victory.