There may be some reasons why naglesmann got sacked.
- Personal problem with management
- Bayern wanna try to play safe by hiring a coach that already won UCL
As far as i can see the performance from bayern under naglesmann is not so bad at all.
Bayern is still able to sit in second place under dortmund which has only 1 point gap. It seems like there was a personal problem between naglesmann with bayern. It will be a very bad thing if the performance of bayern under tuchel will be as bad as chelsea.
Bayern has different qualities compared with chelsea and i think that will not happen for bayern to have the same fate as chelsea. The next match against dortmund gonna be first test for tuchel.
Nagelsmann lost power/contact with the team. Plus, there were clashes with Neuer, in general there were many reasons, but all of them did not concern sports performance in my opinion - Bavaria has 8 wins in 8 games in the Champions League, while the rivals were PSG, Inter, Barcelona. These are good indicators and it is very strange to fire a coach about whom it was stated that "this is a long-term project, a contract for 5 years etc." Bayern's bosses know better, but if Bayern can't beat City, everyone will blame them.
Regarding Nagelsmann, I think the moment when the started the story with Neuer and then the other players, as a coach he need to have a good relationship with players, and this will have a positive effect on the team. Otherwise, the coach will lose his power, and time after time the team's performance will decrease. I think it could be a better option to give Nagelsmann time until the end of the season because Tuchel can't be guaranteed yet.