They lost to a better side because the Leverkusen side happens to be one of the best teams in Germany right now and in Europe at this point in time, and they have been performing very well this season more than Bayern Munich in the champions league and were able to oust Bayern Munich from the German cup this season and, I think this recent development might stir up Bayern Munich to fight harder for the bundesliga title because it seems that this is the only trophy they might lay their hands on as they have been very consistent in this particular campaign this season and have been able to maintain their position at the top till this moment.
Manuel Neuer's red card in the first half of the match between Bayern Munich and Bayer Leverkusen was the game changer. Bayern had to struggle to defend well and also made some attacking moves because they were in short of one man and playing with Bayer with ten players is difficult. Bayer is an attacking side and would have scored more than one goal if not for the quality of Bayern. Heidenheim should be a hard nut to crack for the Vincent Kompany side. They are in sixteenth position and have not won any game in five matches. I would gladly bet on Bayern but it is also important to know that just like other sports, football is unpredictable. Bayern is still in good position in the UCL, so they are still fighting for more than one trophies.