Barcelona won the La Liga last season but with the way they are performing this season, nothing good can be expected from them this season as well. They lack a great finisher and have considerable weaknesses in their defense as well. They enter the field with the same strategy to catch every match. To do well in major tournaments, Barcelona must work on their weaknesses as well as change their tactics, only then will they be able to do well. Barcelona is a big name for those of us who follow La Liga regularly and we always have a bit higher expectations for Barcelona but currently Barcelona are not able to perform to our expectations at all.
I still feel that winning La Liga is not really a benchmark for the Champions League especially for the Champions League is a collection of the best clubs that are in European competition so for champions in domestic competitions such things become commonplace here because after all some clubs like Napoli, PSG, Bayern and Manchester City also have the same title in domestic competitions.
On the other hand talking about the current performance and referring to a change in tactics for Barcelona I think is a little difficult. Tiki taka is the hallmark of Barcelona and indeed they are very good at doing this scheme it's just that for now their players are lacking which makes their tiki-taka hampered. Some players are still not even able to appear in Barcelona because of their injuries which make the tiki taka conditions disturbed. In addition, their progress in goal productivity is now a little faded because Lewandowski still cannot contribute more this season for several reasons such as adaptation after injury and age which is no longer young. Rather than changing their tactics it would be better to make some emphasis especially on motivation as this is quite important in my opinion considering they cannot buy players quickly due to financial constraints.