I wouldn't say Leverkusen's performance as a team that won the Bundesliga trophy last season is mediocre at the moment. They are still playing well, it's just that their performance is not as good as last season. If Xabi Alonso gets the players he wants in the transfer market later, maybe he will fix his shortcomings this season. Although they are behind Munich in points, they still maintain their position in the standings well. Their chances for the Bundesliga trophy may be getting smaller, but they still have other competitions that they can try. So does Munich.
Yes, the transfer market will provide an opportunity for Alonso to buy some players needed so that Leverkusen can perform well. I am not saying that Leverkusen's performance is bad. But compared to last season, Leverkusen did experience a decline in performance. But they managed to beat Munich in the DFB Pokal which means they have managed to eliminate one of their toughest rivals to win the title. So far, Leverkusen has also performed quite well in the UCL by being in 6th position in the standings which means they will qualify directly for the next round.
That's what I mean, Munich lost the chance for DFB Pokal. But they still have another opportunity for the Bundesliga and Champions League, although they have to try harder.
While Leverkusen got another chance in the DFB Pokal and Champions League, Every team is trying hard to beat their rivals and for the glory of their team.
Munich still has a very big chance for the Bundesliga, something that was very difficult to get in the competition last season because of Leverkusen's dominance. And this season they are the ones who hold the dominance, hopefully, they can be consistent.