I don't know what Tuchel should be thanked for. This data is so clear cut that nobody should actually come to the conclusion that it was right to fire Nagelsmann based on that data alone. There might have been other reasons, but Tuchel hasn't achieved any improvement or progress at all. He achieved the opposite and almost even lost the Bundesliga title, but Dortmund came to the rescue.
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.
Now in hindsight it makes fun to think about Tuchel and what he probably thought and expected when he got this phone call and was asked whether he wants to become the coach of Bayern Munich. He was asked when Bayern was in all three competitions and he knew that this could be a very quick and short way to win three titles that some other coach has prepared for so far. They just eliminated PSG and got to the next round in the DFB Pokal being up against Freiburg. I am sure that Tuchel was a bit dreaming and thought that this chance is very unique. But he then ended up in a drama that he didn't think was even possible.
And the question now is whether he still thinks that Bayern Munich is this superior team that he thought it is. He said he fell in love with the team and it is among the best of the best in Europe and so on. But the reality is a bit different as they suffer from inconsistency a lot. The next season will count and I am curious to see how they will be doing.