I think the team that Xabi has only needs some slight changes, not a total overhaul of all lines. They have good players on the team. However, their performance may have changed with the implementation of the training patterns and game strategies applied by Xabi. They need to adapt and quickly adjust for team cooperation. Managing good players is certainly not easy.
There are players who become very good thanks to a lot of media attention, but when you look at them more closely, you realize it was a lot of media attention. For example:
Rodrygo = 90 million euros market value
Mohamed Salah = 50 million euros market value
These two players play the same position. Rodrygo is much younger, but his marketing is greatly inflated compared to Salah, who plays in a very competitive league and has scored many goals. If this were Real Madrid many years ago, they would have a player of Salah's caliber in Rodrygo's position. The truth is that in Real Madrid's attack, Mbappé is the only one who should be left. Along with this new player, the other forwards should set themselves goal targets. It's as if, by mid-season, they don't score at least 12 goals next season, they'll be sold.
Ancelotti managed to survive with this squad because he's a genius, but an ordinary coach won't be able to achieve good results with the current attackers, with the exception of Mbappe. Look at the Club World Cup matches; they failed to score against PSG, showing major weaknesses in attack. During Benzema's time, when he was injured, the attack was terrible. That's why they signed Jude Bellingham, who arrived and scored goals. He did the job that should have been done by Vinicius Jr. (another player with a lot of inflated marketing) and Rodrygo.