You can look at objective stuff as well, such as xPTS in which Barca outperforms Madrid both this and last season.
Anyway, this type of reasoning is a bit difficult when it comes to Madrid because they're probably the most prolific game raisers in the world. It's not enough to just play better than them because if there is one team you would trust to score worldies and grind out wins by being focused in decisive moments, it is them. That's the type of stuff that's not reflected in statistics or highlight videos but something intangible. That's also why they are so good in the UCL, in my opinion. I don't know how they do it, maybe it is the culture at the club or the fact that players just ooze self-esteem when playing for the biggest club in the world but they, but this is a very real quality which is not reflected in most statistics.