Xabi did not have the opportunities that Tuchel had. We realized that Xabi's scouting staff, team coaches and technical knowledge are very good. It is not easy to create a squad that can compete with Bayern Munich. Xabi achieves the difficult. Leverkusen became a better team than Dortmund thanks to him.
Xabi Alonso presence is important, there's a whole lot to learn, Alonso increased the team's performance to an exceptionally high level, but he still requires ongoing commitment from the players to enable them to stand towering until the end of the season. As an outcome, we cannot use one season to validate Bayer Leverkusen's competitive status because this is the first time they have been in this outstanding condition, and there is a high likelihood that the team will win major titles and then flop the following season, that's basically what happen to Chelsea and Napoli.
The fact about Xavi Alonso is he is still a young coach and he is not experienced a lot which means this coach can even have better performance if he gets experienced and starts working in some other teams.
Maybe that's a good reason to say other teams like Real Madrid and even Bayern Munich are going to show even more interest in hiring Xabi Alonso soon.