With Real's current squad, I only appreciate their midfield and attack. As for the defense, which is a patchwork due to injuries, I'm worried about how they will perform in the near future if this transfer period they decide not to bring any central defender contracts.
Real Madrid are quite confident with their options at the moment and it is unlikely they will undertake any transfer activity in the winter to add a defender. If later Real Madrid loses another defender due to injury, they still have several young players from the academy to overcome this. I understand it won't be strong enough but at least Ancelotti understands better what is needed on the pitch and if the coach wasn't Ancelotti it's possible that Real Madrid would have made an emergency transfer to overcome the lack of defenders.