it's all about perception. barca was still perceived as the best team in the world because of the historic 08-2012 years that preceded the tito era. the perception was further compounded amongst the general media because we managed to pull a 4-0 against an above average (at best) milan side. if one took a truly objective look at the 2012-2013 season, then it was apparent we were no where close to the best as we were regularly losing big games and struggling to get past the likes of PSG.
in many ways, the hype about the current bayern side is reminiscent of this. their domination during the 2012-2013 season under jupp has created the perception that bayern is largely unbeatable despite the thrashing they received from madrid last season. the current bayern team is undoubtedly very good but objectively speaking, barca is the best team in the world at the moment.