You made interesting points mate. Leverkusen under Xavi Alonso was a terror to Bayern Munich and that made the Germans bundesliga once again interesting to watch as it was no longer a one man show as it was for many seasons. So if Leverkusen has to lose form this season and give a lower performance from what they gave last season then the bundesliga will be back to it's boring one man show league again, and this isn't what we wish to watch this season.
If only Ten Hag can fix the team and buy the necessary players that will boost up the team performance. Currently. Leverkusen is in the hands of a coach that no one can guarantee his success with the club. I hope that their performance doesn't decline too much this new season. Of course, there is no team in Bundesliga that was able to snatch the title from Bayern Munich apart from Leverkusen. I feel that the league will go back to her old days.
Even when Xabi Alonso was with Bayer Leverkusen last season, their performance declined to the extent that if Bayern Munich dropped points, Bayer Leverkusen would not win their match even though they were playing against a weak team, which is one of the things that made Bayern Munich win the German Bundesliga title last season. Next season Bayer Leverkusen's performance will decline more because they will be without their best players, and they have a new coach, whom people doubt will succeed at Bayer Leverkusen.
I think Leverkusen was terror to Bayern Munich when Xavi Alonso first came but in the following season they dropped in their performance which is why Bayern Munich successfully won the Bundesliga title. So at it is now I see Bayern Munich been the favourite to win this season again because I haven't see any strong challenge for them. Leverkusen can stand in that position any more because they started failing since last season, and this season is about to start and Leverkusen are having new coach which everyone don't have confidence for just because they knew him right from Manchester United and he performed badly. Despite that I still don't underestimate him because football is full of surprises he may get along with his players at Leverkusen than Manchester united players now and the result will start shocking everyone.