Just because Leverkusen retained their manager and also most of their players by the looks of it, doesn't mean that they are going to be able to provide the same results. Sometimes you can keep everything exactly the same and you may still end up losing, we shouldn't really be worried about it.
I believe that the best thing to do would be just letting them do whatever they want, and I am sure that in the end they will do alright. Maybe they won't win the league, or maybe they won't win anything else, but I think it should be noted that we are talking about a situation that is going to be fine. I think it's clear, and we should be quite happy about it as well. Because we would be bored if one domination ends and another starts
Bayern Leverkusen's impressive performances last season saw them win the Bundesliga title and stay above defending champions Bayern Munich. But maintaining this same consistency next season will certainly be a difficult task for Bayern Leverkusen. It seems to me that Bayern Munich and other teams did not plan against Bayern Leverkusen last season which is why they won the league title so easily. But next season will surely see this team as a tough opponent and accordingly try to give importance to this team and then try to perform like that. The next season will probably be a tough competition again between Bayern Munich and Bayern Leverkusen.