Anyone who has been following La Liga for a long time will know that Barcelona is a club that has always rivaled Real Madrid for the La Liga title. I don't believe Barcelona was underestimated in La Liga last season; they only had a bad season in all competitions, which made them less competitive in all competitions last season. The tactics of Barcelona's new coach have helped Barcelona return to its winning ways and also make this La Liga season more competitive than last season. If Barcelona is consistent with their current form, Real Madrid will find it difficult to overtake Barcelona at the top of the La Liga table.
The major cause of Barcelona drop last season isn't stillclear to me though or let's just say they truly had a bad season just like you mentioned and remembered that the season Xavi joined the club they won the laliga but the following season which was last season I think turned out to be different. I don't know if same is going to repeat itself but I doubt it actually because I know Flick is more experienced and I could recall that the financial situation of Barca wasn't in a bad shape while Xavi took over but it's was in a critical state when Flick took over and still maintained it well, I guess that should explain alot...
In my opinion this is clearly Xavi's fault and he should be blamed, after Flick's arrival there was an extraordinary development for the Barcelona team, it is clear that Flick overcame Barcelona's difficulties with his strategy which is quite worthy of being rewarded for him, indeed under Xavi there were many great players but he did not take the good ones but instead felt the lack of players but under Flick many young players entered as starters and that shows that trust in the Barcelona academy is high and I think there will be many more names that enter the first team under Flick and Barcelona can save on purchase costs because Flick can overcome that with young players. The 3-0 win over Alaves saw Fort name Flick's trust at RB clearly show that Flick has a lot of faith in young players and Casado and Cubarsi also look very good and I think under Flick they will overcome the financial problems again and will also move forward with young stars but if you look back there were not many names that Xavi promoted but instead there were many big names that he wanted and it made Barcelona financially difficult but Xavi also did not give Barcelona much and I think under Flick they will have a lot of trophies.