It won't be easy for Ten Hag because several players have left the team which will certainly impact Leverkusen's performance next season, Ten Hag's failure at Man United will certainly always be remembered and that is what causes many doubts now for Ten Hag, I am the same, I doubt that Ten Hag can continue Xabi Alonso's work.
There's no also guarantee for the available players of Leverkusen can fit Ten Hag's strategy well. So, this obvious he must be building back Leverkusen in the way he wanted. Only hope Leverkusen to provide his whitelisting players such as Antony. Still hope to see goat to join them.
The only thing that you must remember is that the different coach, different approach. This is obvious Ten Hag won't be working in the same frame work as Alonso did.
If they play the match with hard work and good performance then we can consider them better than Manchester United. But the way Leverkusen plays and is strengthening itself by working hard, it is difficult for Manchester United to win. If they play well compared to some teams then they are really correct doing it. This is also a good decision because they are keeping all the players in their team who are good and fast players. Now it depends on them what kind of players they want to add.
This is a decision for each team and they are providing better things for their improvement. This is their biggest mistake because if they don't improve in this then only they will be able to play strong and well otherwise they won't be able to match this player.