Xabi Alonso has hardly spent time with Real Madrid, and I don't expect him to come from Germany and win CWC with a different team entirely within few weeks of his arrival. That's not possible, he is not a genius. Every coach has what works for them. Real Madrid players need to understand Xabi new football strategy and adapt to it for further improvement in their performance.
Xabi Alonso's strategy is not much different from Ancelotti's, and it shouldn't be difficult for the players to adapt. The most striking difference between the two coaches is their approach, as Xabi Alonso prioritizes youth, while Ancelotti fully trusts experienced players. The 4-3-3 formation is also used by both coaches, but Xabi Alonso prioritizes possession and dynamic attacking, while Ancelotti prefers flexibility and counterattacks. Success takes time, and I believe Xabi Alonso will achieve it slowly at Real Madrid.