Barcelona probably play 60+ official games during the course of a season. Burnout is an understatement, the way he's involved with analysis, training, coaching and managing the team is beyond the imaginable. He pretty much works 12 hours a day 7 days a week, he has taken 4 weeks holiday over the the last 5 years.
Same goes for the players, never has a team dominated domestic and European football in such a way before, it's only normal for them to have a bit of a blip after playing football at such a high level virtually uninterrupted.
...come again?