As amazing as Barcelona was for 3-4 months, they're only leading their league by 3 points over Real Madrid (although they have a game in hand).
I love watching Barcelona play, but they're not head and shoulders above any elite team in the word right now.
A team like Inter has dominated Serie A for the past 3 years, but you always expect them to flame out in the CL. I would never consider them a top 5 club in the world. If Barca flames out next round against Chelsea, how could you consider them the best?