In my opinion, Duo Joao has no other choice at their respective clubs, therefore, when Barcelona needs their services, they are hungry to maximize this opportunity. If you look at how happy Joao Felix is at Barcelona and not only Xavi is helped by his presence, several other players also feel the same way and can both maximize each other's goals. At Atletico Madrid Joao Felix's role was very underrated and at Chelsea his role was not that prominent so when the offer came to play at Barcelona he was very enthusiastic. Any club facing Barcelona will definitely be reluctant to see the composition that Xavi currently has.
Xavi is one of the best coaches in the world not just because of the quality of Barcelona but his relationship with players. He is an emotional coach who understands the travails of players. We might say that he went for João Cancelo and João Fellx because they are cheap and suits the financial strength of his club. But he just gave these maltreated players a lifeline. Both Joãos were facing several challenges in their club that could lead to the end of their career but Xavi selflessly came to rescue them. Xavi has started reaping a bountiful harvest for believing in two players who were highly maltreated and underrated. Felix scored in Barca's game against Real Betis and provided the needed assistance for Robert Lewandowski goal. Concelo was solid in the defense helping Barca to get a clean sheet.