Yes they lose the solid base they have with Xabi Alonso but i feel like they buy some other really good players to cover the spots left behind by all the leavings, so i cant take that as a excuse, plus Erik Ten Hag have a ton of money to spend after a lot of departures from the team as we saw.
Lets see the new coach how resamble all the team.
The transfers they made were not too bad but also could not replace the positions that had been left, just look at the 14 players they brought in, most of them were young players, the only experienced player was Lucas Vazquez but even that was not enough because he was already 34 years old. It was clear that Leverkusen needed more time to be able to compete tightly under Ten Hag hands but something happened, Ten Hag became distrusted with his vision by management, the dismissal occurred and it was a good and brave move. Rumors say that Ange and Xavi are candidates to replace Ten Hag.
I think both candidates would be good for Bayer Leverkusen. They have European experience and have won trophies with the teams they've managed. Bayer Leverkusen needs managers like that. I still don't understand why they initially chose Ten Hag. They dropped points in two league matches for no reason. Of course, similar things may happen with the new manager, but the Dutch manager already demonstrated his lack of success at Manchester United.