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.
The failure at Manchester United has really tinted his reputation and now the doubts about his ability to get Leverkusen to doing better than they are already, this is his chance for him to prove his ability to do better than. What have been known of him in Manchester United all this years. I do not want to doubt his abilities in Leverkusen by trying to compare his past performance in his former club, after he left Manchester United he had some time to rest and he must have used that time to carefully examine his performance so far so I believe he may do better in Leverkusen.