I think no matter how many points they collect at the end of the season, they still only end up second in the Bundesliga this season, and of course for a team as big as Bayern Munich it is a shameful result, I think if you say Bayern Munich's failure is due to the good performance of Leverkusen, isn't it tantamount to you showing how comfortable Bayern Munich is in the league so far, So they did not expect if there would be surprises that happened like this season, but still in this case Bayern Munich could not deny if their performance dropped dramatically this season when they lost to Dortmund after 10 seasons of dominance.
Actually you're wrong, there are still 7 weeks to go which mean the maximum points they could earn up to 21. If Bayern Munich win at least 5 matches and Leverkusen lose streaks, Bayern Munich will become the winner.
Obviously Bayern Munich weren't expecting they can be beaten up like this, especially with an unknown team that never become a champion in Bundesliga.