When Xavi came Barcelona were 10 points behind Real, now they are 18 points behind (I think that Barcelona is unlikely to win the "spare" game against Sevilla). This is a good argument to blame Xavi, but if you look objectively, what opportunities did he have? Barcelona's squad leaves a lot to be desired and it is possible that positive changes will come only after new players are acquired.
Behind 18 points with the leader of the standings makes Barcelona have to bury the dream to compete for the La-Liga title this season. Xavi arrival is expected to have a positive influence on Barcelona poor performance when Ronald Koeman was still Barcelona coach. But so far Xavi has not been able to provide the best for Barcelona. Defeat after defeat becomes a bad gift for Barcelona management. Joan Laporta must move quickly to bring in new players, Erling Haaland is considered the right striker to strengthen Barcelona attack line. Ferran Torres is also a target for Barcelona. But barcelona had to make big sales to get fresh funds to get their coveted player.
I think that even the most optimistic fans did not think about the championship even before the appointment of Xavi - Barcelona lagged behind too much, but besides that, even from the composition of the team it is clear that the club will not claim titles this season. Xavi's appointment (with his training system and emphasis on building team cohesion and discipline) seems like a long-term strategy, perhaps Barcelona wants to nurture a new generation of champions to replace the one that gone. But undoubtedly, some of the players they will still have to buy.