According to a report from Mediaset, one of the reasons Juventus intends to introduce Alaba is that Alex Sandro's performance is not particularly convincing.
In addition to physical problems, Sandro's performance last season was not particularly convincing. At the full-back position, Frabota is still too young to meet the requirements of the Juventus Champions League. Quadrado is not a full-back, so Juventus intends to introduce Alaba.
Alaba has proven himself in Bayern, and he can also serve as a central defender, which is very in line with Juventus and Pirlo's system.
The relationship between Juventus and Bayern is very close, and the recent Douglas-Costa transaction has also proved this. Therefore, the two sides may reach an agreement in January next year, and Alaba may join Juventus in the winter window.