Barcelona was already a famous team. He didn't become a famous team with Xavi. It made people wonder if he could catch up with his past successes with Xavi. Barcelona's history is full of great achievements. They had great years, especially with Ronaldinho and Messi. In recent years, they are not what they used to be, but this situation may gradually change.
Xavi was able to get Barcelona back on track because before he joined the team, the impact of the financial crisis was very strong. Thanks to discipline, he managed to return good results, retain players and replenish the team with new players. Yes, Barcelona used to have Messi, but now they have Lewandowski and Gundogan, if that's not enough then I'm sure Xavi will be able to strengthen the team even more.