Madrid has a very strong squad. Where is the weakness of this squad? I can't find it. Last season we saw weakness in Madrid's defense. This season, Madrid has bought talented defenders like Alexander Arnold, Huijsen and Carreras. In the attack, there are two extraordinary talents like Vini and Mbappe. In the midfield, Bellingham, Valverde, Camavinga and Tchouameni are all quite talented.
Real Madrid must change their tactics and players in the squad for getting better balance between attacking and defense which they did not have good enough in the past season. Only good balance between attacking and defense systems can help them become stronger when playing against strongest clubs in La Liga and Champions League. That balance will be solid foundation for their good results in matches and success in competitions.
However, Madrid has lost an experienced midfielder like Modrich in the midfield. This may be a weakness of Madrid. However, it is not possible to find a talented midfielder like Modrich. Madrid has a very strong squad. Now Madrid's entire performance depends on manager Alonso.
They already prepared for departures of Casemiro, Kroos and Modric three seasons ago but it's clearly that such players are barely seen so replacing them isnot easy. Real Madrid will need a lot of money spent on transfer market as well as time to find another star player who can reach to similar level of those legendary midfielders.
If you look at their recent matches, you might see weaknesses that Xabi Alonso still needs to address. The midfield is still unstable, and they are missing a key player in the game, which is why their attacking play is less than ideal. On the other hand, the defense hasn't fully improved, despite the signing of several top-quality players. The number of goals and goals conceded can be seen as a form of reference regarding the performance of this team and I agree that Xabi Alonso will start a different era at Real Madrid because maybe changes need to be made to maintain the chance of winning trophies in his first season.
Xabi Alonso still has a lot of time to work with his players, improve them as well as train them with tactics and choose best tactics for Real Madrid squad. A season is long and Real Madrid don't need to be a perfect team at a season start to win La Liga. They surely must get good and acceptable results in early matches in order to not fall too far behind Barcelona in the league table rank, then they can buy time for improvements gradually.
A champion is decided by general and cumulative performances and points in a whole season, not with several early matches, in middle or around the end of season. Both Real Madrid, Barcelona and Atletico Madrid will need to perform almost consistently and excellently during a whole season to win a trophy.