I really don't think so, it wasn't even just this season that ended that Real Madrid started having serious defensive injuries it was the other one. It wasn't Ancelotti's fault that the team was reinforced but the fault of Perez. The coach had requested for the players he needed but the management did otherwise. The coach has no other choice than to manage the players that he already has.
Previously Ancelloti also had a difficult path because a number of players he had were injured but that season they managed to come out as champions in the Champions League. Last season Real Madrid did not take advantage of the transfer market to recruit the players they needed so it was difficult for Ancelloti to compete and I don't think this is entirely Ancelloti's fault. Because in the season that went badly for Real Madrid he did not get the support of the players when he wanted to rotate the defense line.