Nkuku's arrival at Chelsea is a fantastic move for the club, but hoping for too much from him may be disastrous. I don't believe he's ever played in the Premier League, and as we all know, the Premier League is very different from the Bundesliga, from whence he comes. It may take some time for him to learn and bond with the style of football played here. He's a fantastic player, and his move to Chelsea will be fantastic if the coach can put him to good use.
TBH, I'm surprised that Christopher Nkunku really wants to join Chelsea.
We know that Chelsea finished this season with a very bad result, they were out of the top 10 in EPL. In this situation, I assume not many top players want to join Chelsea because they won't play in UCL or Europa League. Top players mostly want to stay playing in the highest competition of football. But Christopher Nkunku thinks differently, he seems interested to join Chelsea because he wants to help Chelsea to be a strong team again. Sure, it won't be easy for him, he must take time to learn and adopt with Chelsea game play.