Time is exactly what Erik Ten Hag needs to boosts the confidence of the players. Manchester United won the FA Cup with what form exactly? Erik Ten Hag have succeeded in elevating the performance of the club and they're currently improving in all sectors. Before witnessing the standard form of the club, Manchester United needs to make good runs when it comes to signing players.
Eric Ten Hag is not really the best guy for Manchester united, he's only managing that position to my own opinion because if he was the best for them, winning FA Cup would not have been the only thing to celebrate for them. I agree that was a great height but that's not just it. It could have been bigger for them. Maybe they would have moved closer in the table standing if they were more consistent in their goal streaks.
Every team do have their good and worst season and Manchester united are currently experiencing the worst we can see them be. Very good he was given another opportunity to build his team better. Winning the FA cup is not an easy task because many other teams competed for it, even victory at the finals over the Premier League champions still shows they have lot of room left to improve in the coming season.