Jurgen Klopp going to Bayern Munich? He will fit in so well and also become a more better coach than Jurgen Klopp who's probably overhyped due to the fact that he lifted the UEFA Champions League title in his first season as Chelsea manager, what happen to an elite team like Bayern Munich, where it would have been an easy race? Bayern Munich was not good enough last season, they didn't sit in any solid position to win the Bundesliga title but due to the crucial mistakes made Borrusia Dortmund, Munich was crowned the Bundesliga Champs because the best results are yet to come.
Considering his history, I doubt Klopp would take that job. He managed Dortmund before, plus some interviews show him laughing at Munich's losses iirc. I believe he will just go straight to the national team if he even considers coming back to football, or becomes a pundit maybe.
As to why Bayern has had a bad season, one of the possible reasons is their latest recruitment doesn't work out and their existing players have a dip in form. It is unrealistic to expect all of them to perform at their best every matchday anyway. It might have to do with the coach too, who knows what's happening behind the scenes. Not really surprised if there is a clash or just an inability to do what Tuchel asked them because they don't believe in it or something else.