Xavi Hernandez since he took over the managerial position at Barcelona has significantly improved the general performance of the team and with what he's achieved so far with the Barcelona squad, I think they're strong enough to challenge for major titles but I think they still need more improvement to be able to challenge for the UEFA Champions League trophy.
They played against their long term rivals Real Madrid today in the Spanish league and were beaten at home by the Real Madrid. Though their defeat today doesn't necessarily mean that they're a weak team but I think they aren't good enough to challenge against European giants like Bayern Munich, Manchester City, Paris Saint Germaine and Real Madrid.
He's the tight manager for Barcelona cause he's coaching them with same experience he had as a player for the team, if only the team was very financially stable to strengthen the squad depth to the standard Xavi would want, however he's managed the squad he has and even became successful with them last season by winning the Laliga trophy, well last season Barcelona was not very impressive in the UCL competition, they focused all their attention in the League games and that's why they won it.
However this season Xavi has recruited some new players to help him in both the UCL and domestic league game, although his team needs more strengthing like a good younger finisher that would replace Lewandowski and last them long term and some defenders also, however they still look tough and capable of challenging in any competition.