for now, barcelona is one of the clubs with the best squad in the world so if they intend to buy players again, it's just a waste. What Xavi has to do right now is focus on making the current squad work very effectively. they must be able to at least win a domestic trophy in the following season and the UCL is one of the trophies that Barcelona must target.
The best in the world 
I think Barcelona is only the best team in La Liga not in the world because the best team in the world for the season that has ended is the English team that won the UCL two days ago. So how can you say that Barcelona is the best team in the world if Barcelona still failed in the UCL and have to try again next season. After all, the nickname of the best team in the world is a team that can get three trophies like what Manchester City got this past season. Not just one trophy, namely in La Liga.Barcelona won't be proclaimed the best team this year, but you can say that they are the best team in the LA Liga this season, if not the entire world. Any team can win the LA Liga the next season, therefore winning it shouldn't make us think Barcelona are the best. Did you know that the team that won the LA Liga championship the year before wasn't Barcelona? There is no need to go into great detail on the topic because we all know that we are talking about gaming.
The only time Barcelona is the best team is when Messi is on the team, but they can't even make it to the semifinals in the current champion league, so I'll be interested to see how they perform in the upcoming season.