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.
The EPL is tougher than we're just seeing. Manchester United worst season, they've managed to record winning and also lifting the FA Cup. This is a direct message to some elite team that have claimed to be in their best season but always messed up. This is really a challenge for Erik Ten Hag and also a change of story for the headcoach, he earned another season to manage the Red Devils.
EPL is a very tough league compared to other leagues, if they should send any Premier league team that is below 15 position on the table to other leagues, they will do better and win those trophies. You mean elite teams like Arsenal and Liverpool, Arsenal should be the EPL winner coming season except if Manchester city decides to change their fate. Ten Hag should do better than this, a lot is expected from him.