#3 Lack of stability
A distinct lack of stability and structure at the heart of Real Madrid after the departure of former coach Zinedine Zidane played its part. The change of managers and formations in the middle of the season did not help Los Blancos' case.
Under the tutelage of Ernesto Valverde, Barca players have looked confident and stable enough to not lose once against their eternal rivals. It was as if the Barcelona players knew what to do and the exact moment to do it, which eventually resulted in clear domination.
Moreover, each and every substitution of Valverde worked like a well-oiled machine, whereas Solari's changes had a desperate mark. Despite notable positive changes from Santiago Solari, the players were seemingly unsure, as they always found themselves a goal behind, and clueless on how to reply to the situation.