Yea the work here will be very easy for Ten Hag because he met a good team just as you said but this will also expose many things about him if he is actually a good Manager or not, despite anything I think he didn't do much for Manchester United,
The condition of the team will always be different when there is a new coach. Even though they have a good history, it could very well be different. There are two possibilities: they will either improve or deteriorate. I feel disappointed with Ten Hag because he failed with Man United, so there’s speculation that he might fail at Leverkusen. But that’s just speculation. I feel confident that Leverkusen has chosen him and is ready for the risks. Leverkusen is also prepared with fresh funds after Florian Wirtz officially left. Reportedly, Leverkusen is preparing €70 million to bring in another star. It is said that he is the Monaco star Maghnes Akliouche.
Source:
https://www.goal.com/en/lists/big-signing-erik-ten-hag-bayer-leverkusen-eur70m-monaco-star-rebuild-mega-florian-wirtz-sale/blt36c3b6d05349f64d#csfed62d8088537ae0