Tuchel did not have much time in Bayern Munich before some important matches in Champions League and Bundesliga. First he brought hope to Bayern by directly beating Dortmund. Later Bayern got unstable performances and they luckily won Bundesliga at very last minutes of the season with a genius moment from Musiala and very poor performance from Dortmund.
Thats true and he was thrown into the cold water when toke over the Team from Bayern Munich at this time.
About the unstable performance i guess that was already because there was something wrong in the Club specially on the managment.
That Bayern Munich has won the title was only a gift from Dortmund , nothing else , and lucky that Musiala showed his skill at this time.
If Mane plays better and if Bayern find a good striker to replace Lewandowski, Bayern Munich will become a stronger club in a new season and they will dominate Bundesliga again. Their chance in Champions League will not be small because in a new season, many big clubs will be in transition phases like Real Madrid.
Yes a lot of Teams will making od have already maked some changes to there Squads.
The cards are all reshuffled.