To assess Bayern Munich's performance through coach Thomas Tuchel is next season, not at the end of last season because time is so tight that there is no performance that is more worthy of evaluation in general. Thomas Tuchel needs to deploy the Bayern Munich team next season, especially in the Champions League because Bayern Munich always looks better in the Bundesliga so Thomas Tuchel only needs to polish his players to face the Champions League next season apart from the Bundesliga.
Tuchel has a rather difficult task and in many respects it depends on luck. Firstly, the title in the Bundesliga will not be perceived as an achievement - this is what should be in any case. He is more likely to be judged by his success in the Champions League, but much will depend on randomness. Even this season, Bayern already had a difficult (as everyone thought about PSG) opponent in the 1/8 and theoretically this could happen again. If Bayern get knocked out early then it will be considered a failure (and most likely result in a sack) and if they are lucky like Inter and make it to the final then it will be judged as a +- success.