We don't know why Nagelsmann was fired. But the decision to fire Nagelsmann was not correct. Bayern Munich's performance further deteriorated after the sacking of Nagelsmann. They were eliminated from the Champions League after losing badly against Manchester City. Bayern Munich's performance in the Bundesliga was not good either.
Tuchel in Munich is not yet successful. Out of 12 matches, Bayern Munich has won 6 matches and lost 4 matches. We are not sure if Tuchel can strengthen this team next season. But Tuchel is experienced enough. Hopefully, he will be successful with the Munich team.
It has been stated so many times in the various articles that published by various reliable sources if naglesmann has been sacked due to the inconsistency with the club. He has been sacked when he was playing ski after he got a call from bayern's director.
That's why his case has become very popular case at that time. As far as i remember if bayern has 100% WR in UCL under him but tuchel wa destroying it in the first touch with bayern in UCL when it faces manchester city.
I remember how optimism tuchel to beat manchester city but it's ended with pathetic result.