Pep Guardiola always uses tight pressing to find box to box gaps for his players to be able to achieve precise attacks and that is why Manchester City can win the Champions League this season. Xavi must immediately evolve with his players so as not to be left behind by his competitors, especially Real Madrid, who will not be playing anymore to be able to win the Champions League title again.
What works for Pep Guardiola might not necessarily work for Xavi if he can’t employ the strategy very well. Anyone can have a different approach in the style of play in the field and it’ll work for them both. What is more necessary is to be able to use your strategy well and also be able to counter your opponents strategy when they come striking (attacking) at you back. I don’t see anything wrong with Xavi’s coaching style, he just needs to know how to use it well in the champions league game too.
Indeed, there is nothing wrong with Xavi's strategy, but sometimes it is quite difficult to win, and they have only been able to score an average of 1 winning goal in every domestic league match this season. Therefore barcelona will only be able to master Spain and for the champions league competition they are still not able to be consistent.
I think if barcelona is still in the same form as last season then there will be no change for the champions league next season. It has been proven that Barcelona really needs new players to be able to rotate their players in order to get better results, but we also know that this club is also in financial trouble, so that is quite impossible to do.