To be honest, Barcelona's performance in the Champions League was great, but somehow they struggled to win 3 match in a row so far. They may have been unlucky with the group draw this season, but that's not a good reason to justify assumptions about why they failed.
Bayern Munich and Inter are apparently still very strong for Barcelona, so it would be better to expect them to come home sooner than fall short in the last 16 against the likely title favorites this season. Barcelona have very little chance of qualifying, it's probably around 20%, and the rest they will probably head for the Europa League.
Barcelona does control the field, because the style of play they apply will increase the percentage of possession. But in the champions league it is not ball possession that is desired in the field. Because some clubs that are included in the champions league will not serve that kind of style of play. They will continue to make breakthroughs with Shots for sure.
Back to the topic of LaLiga.
Barcelona have yet to meet Real Madrid as eternal rivals, and we will see El-Clasico drama. So we will see that as a determination of the performance that comes out as the winner this year.