Last season most of the errors and games that Real Madrid lost was as a result of defensive errors and injuries on their defenders now since they have a replacement for their former coach the new manager has made a very good signing in that regard to insure they don't experience the issues they had last season by bringing in more defenders in the team.
But Alonso should also note that depending on the formation of the former manager may not work for him so he needs to have his own formation and the tactics get will work for the team. He can choose to return all the players that has been removed from their main wing back to their wing by doing so everyone will be at his best and their won't be any competition on the player that must be a regular goal scorer for the team.
real madrid's weakness lies in their back line which is often conceded, and some of their players are often injured, so that it makes their performance quite bad last season. and now xabi is rejuvenating the back line and making some significant transfers to fill the back line. several young players such as dean huijsen, trent alexander, and álvaro carreras, are expected to be able to guard real madrid's back line and make their defense better.
and about strategy, i think that xabi definitely has the best strategy for the team. especially when he was at bayer leverkusen he had a progressive game, which was structured and more pressing. maybe he didn't bring the strategy to real madrid, but with a few adjustments and optimizing the role of key players, he should be able to get the best strategy for real madrid next season.