#2 High defensive line
Conceding goals had never been a major problem for Real Madrid, as they always managed to outscore opponents. Unfortunately, this has not been the case this season.
While keeping majority of the possession, the team's defensive line tended to go higher up the pitch. This made the team weaker when opponents counter-attacked. This was how most teams scored goals against Real Madrid.
Teams like CSKA Moscow and Levante dominated Real Madrid at the Santiago Bernabeu. Their huge possessions led to nothing, and opponents patiently waited for the right moment to counter-attack and score.
Lopetegui made world class defenders like Sergio Ramos and Raphael Varane look like Sunday league players. With continuous and clueless side passes, the opponents were easily able to counter-attack, again and again.
Every time a midfielder displaced the ball, the opponents were able to take advantage of that opportunity and create a chance of scoring.