Barcelona won this league and this can be a great achievement for Xavi and his players especially when we know Xavi won the season while didn't have a good financial situation compared to Real Madrid. Barcelona also failed to hire Messi, I think Barcelona will have problems for the next season because they don't have enough good players and they need to hire many players at least they need to hire a forward to have a young alternative for Lewandowski.
It's nothing extraordinary when Barcelona dominates LaLiga but loses in every other competition, unless Barcelona win two trophies then that's even better. Also, Barcelona's finances have basically recovered a bit because Barcelona have also managed to recruit new players like Lewandowski for example. So, Barcelona's success this season in LaLiga is a natural result, because Barcelona also has improved finances. Also, Barcelona have had a good squad this season so nothing surprising, as Barcelona have only managed to win the LaLiga title this season with such a good squad.