Even though Barcelona is unbeaten so far, that also doesn't mean Barcelona has a guarantee of the La Liga title this season. Because after all, the evidence is that even though Barcelona has not been defeated so far, but why, why Barcelona not at the top in the standings. Because usually, when a team manages to go undefeated, then of course that team is at the top of the standings, but for Barcelona at this moment, Barcelona current position is even below Girona. Therefore, at least there is no definite guarantee for Barcelona to win the La Liga title this season, because the league is still long, of course Real Madrid also has a big chance of maintaining its top position throughout this season.
A team staying unbeaten doesn't mean they have won all their encounters with other teams, it's very possible a team can continually draw with every team they come across in the season and stay unbeaten and that will definitely not give them enough points to be at the top of the table, Barcelona's unbeaten status this season has some draw which gave them just a point so they can't top with such alone.
I agree that Barcelona is not guaranteed to win the league title this season and ofcourse at this point nobody is actually guaranteed to win either as we still have a long way to go with the season, it's True that cumulative performances from now will definitely have a way in determining how possible a team will possibly win the league title.
Real Madrid at this point stand a chance more than Barcelona does but then since football if filled with so much of uncertainties, it's very possible along the line Barcelona will pick up form again and perform so well they could get a chance at the top and probably be on the race again to win the title, so I think it's yet still too far to be sure who is most likely to win the title.