Xabi has been with Leverkusen for almost 3 years, so he can get to this point in need of a process. So if Bayern want instant results it seems that is also difficult to happen. Because I believe Every coach must have a process, there are not many coaches who can give a champion when he just comes. So if Bayern want him, it is also the same as the previous coach because there is no definite guarantee from Xabi.
I think you might have missed calculated but Xabi Alonso is just into his first full season at Bayer Leverkusen, he joined in the middle of last season (late 2022) when the club were in crisis and were in the 17 place in the league. Alonso who was managing the second team of his former club Real Sociedad join Leverkusen and since that last season the signs were there That he was going to take the club back to where it belong. He almost qualified miraculously for the champions league spot but fell short to Leipzig and had to settle for the Europa league which was also a very impressive result considering where he took the team from.
Yes Coaches need more time in their new clubs to develop something but Alonso has shown that an immediate impact can also be left by a manager, this doesn’t mean he will replicate same at a new club but this has shown that he can adapt early to just any league and club