Did you watch the Spanish Super Cup final which Barcelona just won. Barcelona played like crazy to win trophies, the struggles of Barcelona players were not in vain, they managed to beat Real Madrid with a landslide score.
Let's compare the Super Cup competition with the Europa League, it's impossible that Barcelona don't care about the Europa League trophy. The Europa League competition is more prestigious, of course Xavi will prioritize the Europa League this season, especially since Barcelona failed in the final last season.
I'm sure Xavi's priority right now will be La Liga, especially since after beating Real Madrid they will have enough self-confidence to keep their lead. Barcelona won't mind winning the EL as well, but the first game will be against the MU, who are also in great shape right now and they beat City this weekend. We can say that both clubs are close to their optimal form, it should be a very interesting confrontation.
I agree, it's a lot more important to win La Liga than to win europa right now. However, it is also a great thing if you could win them both. Football is not really as much white/black as people think it is. Many people keep saying "well they will focus more on la liga than europa" type of thing but the reality is that we are going to see them focus on both of them at the same time.
These are professional players, mainly young enough and fit enough to actually play 2-3 games a week and be great at what they do without being tired all that much. Everyone thinks that if you focus on la liga then you will be tired when it comes to europa games but that's not the case, they can give their %100 to both of them.