This is why we shouldn't underestimate Ten Hag. Leverkusen wouldn't expect too much from Ten Hag because they have known his past and hiring him means that they're ready to work with him. On the other hand, Ten Hag will also want to put in the best of his coaching skills into the job, so that Leverkusen wouldn't be disappointed in him.
To be honest, I'm am not expecting much from Ten Hag's next season as Leverkusen manager, and I'll underestimate him, especially since many key players have been moved to other teams and they have yet to find replacements. Ten Hag may be able to win other titles, but I don't believe he can win the Bundesliga or Champions League. Perhaps the Premier League was too difficult for him, and he may do better in the Bundesliga, but I'm wondering whether they can finish in the top four next season.
However, I don't know how Leverkusen management came to trust Ten Hag so much that they hired him after Xabi Alonso gave them an amazing two seasons, considering how Ten Hag bad seasons at Manchester United. When Ten Hag arrived, Manchester United was in the Champions League, and they were easily eliminated, to the point where he sent all of Manchester United key players away due to a misunderstanding he was having with them. The manager, I believe, had a good relationship with the players, and I hope Leverkusen players do not have a similar experience with him.