It's one thing to have a UEFA Champions League experience as a player and also a total different thing to have it as manager but some persons are mistaking it when talking about Xavi Hernandez's champions league experience.
Barcelona is his first club that he competed in the competition with and that's why he shouldn't be blamed to an extent on the club's performance last season in the European Cup. He's been progressive with his Barcelona team and might win the Champions League in the nearest future if he's allowed to continue to develop this Barcelona young team
The current Barcelona squad won't win the Champions league unless a miracle happens, maybe it would take five miracles in one season. They don't have this continuous dominance yet. It could still be possible that they make it through the group stage and then also survive in the competition for one or two rounds, but if they were up against Manchester City or Real Madrid tomorrow, I think it would be pretty safe to say that that is where the journey would come to an end for them.