Believe me, I don't believe that Leverkusen can unseat Bayern Munich.

That's why I asked the question.
Of the 3 games you mentioned, I only see 1 as a difficult game for Leverkusen. Mainz vs Leverkusen, Mainz are one of those teams that we rarely discuss here without realising that Mainz can always beat the top teams when Mainz are at home.
As for the games against Freiburg and Dortmund, I'm sure they won't cause Leverkusen any problems. In terms of performance, Leverkusen are much better than Freiburg and Dortmund.
Besides Bayer needing to win their games, they also need Bayern to start losing their games, because the difference between them now is 6 points, that's a lot, in fact Bayern can lose two games and still keep the first position because they have a better goal difference. And although Bayern have bad games, they are still strong enough to not allow a losing streak and lose the advantage they have now.