Real Madrid's biggest problem is the lack of a central midfield player. Furthermore, I predict Arda Güler will be the player they'll use there, as his defensive skills are quite weak. He's also not as physical as Kroos, so using him in that position would be quite difficult. He could capitalize on his technical expertise to open up play, but Xabi would struggle defensively. In my opinion, Real Madrid needs a defensive midfielder.
It's true that Real Madrid midfield is a major problem, and we've seen that the flow of the ball from the back is often lost once it reaches the middle of the pitch. It's no wonder Xabi Alonso is still insistent on lobbying Madrid for support in recruiting more players. Xabi realizes that the current squad isn't enough to make Real Madrid strong.
I think Real Madrid coach realized this weak displayed during the semi final with Paris Saint Germain players in the FIFA club world cup competition, when their defenders displayed some mistakes that made Paris Saint Germain strikers to scored two goals within some minutes. Real Madrid can come back to good performance if they can decide to replace some defenders before the season start because their defense level is very weak these days, Since the window is still open for teams to sign new players, I think Real Madrid coach will make a good move to add talented players in this summer season, to make Real Madrid fans to have hope on Real to win next UEFA champion League title.
In the match against PSG, we saw Real Madrid's defenders making some obvious mistakes that were actually made by professional players. The poor performance in defense was the reason why Real Madrid lost by such a large margin against PSG. Real Madrid did not only make mistakes in the inner defense, they have been doing poorly in defense throughout the season. Although other positions are strong, I don't know why Madrid's defense always seems weak to me. Although there are enough reasons behind the bad defense position, my question is how long they will play with such a shaky defense. When they see that their important defenders are out of the field due to injuries, they could have brought some defenders to their club for a short time or they could have brought defenders on loan from another club.