Xabi is an experienced coach and I feel that he has been able to figure out that if he uses same formation he used at Bayern Leverkusen for Real Madrid, he may not actually get the result he wants that is why he is using a different pattern but maybe we can wait till next season to see the formation he will prefer. He is coaching one of the best teams in Europe so he will certainly use a different formation that will match the club's style of play. Xabi Alonso has already proven himself at the FIFA club world Cup, despite Raul Asencio getting an early red card in their match against Mexican team Pachuca but they still managed to win by 3:1 and are leading the table of their group so it shows that next season will be a smooth one for Xabi Alonso even though there will be a tough competition between them and Barcelona.
Just like you said, Xabi Alonso is an experienced coach, and as an experienced coach, Xabi Alonso doesn't want to depend only on the same formation he used at Bayer Leverkusen for Real Madrid, so Xabi Alonso is using the Club World Cup tournament to explore different formations for Real Madrid to know the perfect information that will suit Real Madrid. I will not use Xabi Alonso's performance in the Club World Cup to say Xabi Alonso has proven himself at Real Madrid because the Club World Cup isn't competitive enough to give Xabi Alonso the challenge he needs to use and prove himself at Real Madrid, but I know Xabi Alonso is the right man for Real Madrid, and he can guide Real Madrid to win the La Liga title and the UEFA Champions League trophy.