The thing is that management is not only tactics.Tier 1: Klopp, Pep
Tier 2: Emery, Nagelsmann, Howe, Arteta
Tier 3: Koeman
Tier 4: Xavi, Lampard
Xavi isn’t a natural tactician. He can become one with experience, but he made a mistake in assuming too much responsibility early on. He should have worked his way up… like Arteta did (who now has a strong foundation and is continuously getting better.
Comparing Xavi to tier 1 managers is delusional.
In terms of pure tactics Xavi isn't that strong. His main qualities are man management/motivation/discipline, the social skills, which is half of being a manager.
Having a manager who the players believe in and will work for is important. Someone like Setien knows a lot about tactics but unluckily for him he commanded no authority due to reputation so nobody would listen to him.
Xavi having those management skills and his reputation has helped significantly in getting us the LaLiga title.