Its not only about the key and best players that left Leverkusen , the most will be the change of the coach.
For now i would say that it will be very hard the coming season for Leverkusen.
Dortmund and fingers crossed here hopefully will be better in the season.
Leipzig is behind the performance they can do.
Yes, I think there is no doubt in this fact that a coach plays an important role in the build up of any team . Because, the chemistry between the coach and the players should be as friendly as possible. Being with this strong bond a club will be able to perform well. From the Bayern leverkusen many players left and the reason was only due to the coach. So in this situation the responsibility of the coach has been increased to the next level. Eric ten hag as a coach of Bayern leverkusen is a really confusing addition till the signing day. But ETH now should pay his all attention and all skills to raise the team well. And he should try to fill these places which are empty. As the leverkusen team needs a strong striker now to perform well and defeat the opponents.