People are being judgmental on Kompany because he has no good record in the past career that will make them believe that he can revive Bayern Munich from their current form. Kompany was poor in his last management as a coach in Burnley and even made them finish as a relegated team. Even with out a doubt, that is one of the major reasons they don’t see him as the best coach for a big team like Bayern Munich.
Because indeed statistics and previous performance remain a comparison and actually it does not only happen to Kompany but almost to every club even Xabi felt the same when replacing Seoane at Leverkusen 2 seasons ago.
But in the end Xabi managed to provide the best situation and silence the critics who were previously worried about Leverkusen's performance and considered Xabi still not worthy. That's what Kompany has to do now because however criticism will continue to exist before he really proves that Bayern's choice is not wrong with him.
In addition, Bayern is a big club so criticism and concern are clearly felt but on the other hand for Kompany it must actually be used as a whip of enthusiasm and prove himself that he is indeed capable of making Bayern better next season.