#2 A mean defence
The most surprising part of Barcelona's start to this season has been how good the defence has been. The stats are incredible - 4 goals conceded in 11 games in La Liga, 1 goal in 4 games in the Champions League.
Firstly, a lot of the credit goes to Marc Andre Ter Stegen. The keeper has been in astounding form, his saves, especially in the game against Athletic Bilbao, gave insight to as to why he must be considered among the best keepers in the world.
The defence has always been the weak link to this side, because of how high the defence plays up in the field. But this season, the mistakes have not been there and the centre-backs have been incredibly calm and composed in tight situations.
Samuel Umtiti has been a revelation, proving his worth to the team with incredible interceptions and tackles. An example is shown below:
Gerard Pique has not yet hit the heights of last season, but he has barely made any mistakes. Jordi Alba looks like his old self once again with freedom down the left flank, along with doing his defensive duties well.
Sergi Roberto and Nelson Semedo have been very good at right back, with both of them almost always involved in attack and defence. Mascherano has stepped up promptly whenever required as well.
With this defence, Barcelona have the firepower to beat all their major competitors by keeping them at bay, and backing reason #1 to do the job.