When Kompany first came to Bayern Munich, many doubted his capacity as a coach. Not without reason, because before coming to Bayern Munich Kompany coached the Burnley team which ended in relegation because there were no quality players but now he is at Bayern Munich he has everything so he can apply the strategy he has and succeed even Bayern Munich will soon win the Bundesliga title.
That is the reason why Kompany is better at Bayern and is sluggish in the previous club league. The reason is, Bayer with a team that has good finances and classy players, or you could say he is just continuing the previous era and applying the tactics he has. Even now he still has the opportunity to win the champions league even though it is difficult but it does not rule out the possibility that it could happen.
Most football fans didn't actually doubt him, infact most of us knew he would perform well because Bayern Munich is an already made team, coaches really don't need to do much for the success to start coming and showing. His Burnley team were no match for most teams in the EPL that's why he struggled. If you remember before Kompany's Burnley team qualified for the EPL, in the Championship they were rocking it like no mans business, Kompany was already making his name with a team that wasn't really a good match for most teams in the Championship then. But he surprised most of us back then that's why when he picked the Bayern Munich job, we knew sooner or later he was going to strive with the team.
You are right, Bayern Munich is an already established team, just like Real Madrid is and any coach that joins the team will undoubtedly succeed and win a title before the season finishes. Kompany has been performing well for Munich this season, allowing the club to progress to higher tiers of the league and the Champions League. Tuchel tried but failed to assist the team win the UCL he merely won the league title, and I am sure before he ever arrived to the club, they were in fine shape before dismissing their coach and bringing Tuchel in.
Currently, Kompany is in top form and has already predicted that Munich will win the Bundesliga title this season with Harry Kane, as well as the UCL trophy, because they are dominating Bayern Leverkusen in the round 16th home and away, and while Inter Milan is doing well in their league, Munich has a record on them and I believe they will still have the opportunity to defeat Inter Milan and qualify for the next round.
Bayern Munich believes they will win the league title, which is why they did not put too much pressure on some of their league games. Munich will do whatever it takes to get three points in their next game because Xabi Alonso is doing everything he can to top Munich in the league table, which I am sure will be difficult, but anything is possible. Let us see how the season goes.