Bayern Munich's performance has been erratic since the sacking of Julian Nagelsmann. But we can't blame Thomas Tuchel for that.
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.
I think that is exactly why he was hired, so that he would win them UCL or take them higher and he failed because he was just way too new when he first got there. I think it would be quite important to remember that he was amazing at Chelsea before the new owner and he should have been kept there. I actually do believe that he will do as well as everyone claims, Bayern will be a much better team, we just need to give him some time and see how he will arrange the team.
There were tons of problems with the club last year, fired directors, Mane issues, Manager change in the middle, all these are big deals and I feel like that's why they were in turmoil. Next season it will be a better season and they will keep everything under control and be more consistent.