Barcelona was in a terrible state before tht arrival of Xavi. And he is just trying his possible best to put Barca back on track. But, what people don't understand is that this will take some time. Atletico Madrid performance are poor, they lost all their last 4 matches, and one of the problem Atletico seems to have is are defense. However, If Barcelona play their next matches without losing, they will surely take over Atletico Madrid's place.
Maybe in the short term it's difficult. Relying on players from the academy could not guarantee they would be successful. There are a lot of problems at Barcelona so this has an impact on their achievements.
Maybe if for the long term they can be successful again. Attempts to sign Xavi also can not be hopeful, because he is limited by the crisis to choose new players. Xavi is currently only maximizing what Barcelona have.