Real Sociedad can be said to have a fairly stable performance at the moment, because up to this week Sociedad was able to achieve 5 wins, draw 3 times and lose 5 times. Apart from that, I also agree with you, that in some matches Sociedad should be able to win, but unfortunately Sociedad could not win the match, as happened against Mallorca. Maybe if, for example, Sociedad can maximize every match in Laliga, then there is a big possibility that Sociedad can compete in the top 5 of Laliga. But now, after Sociedad beat Barcelona, it seems like a very good first step for Sociedad to continue climbing to the top 5 in the Laliga standings. Because to be honest, I personally didn't think that Barcelona would lose to Sociedad. But the result turned out to be that Barcelona was defeated by Sociedad.
In fact, if we look at ball control in this match, Barcelona really dominated. But Sociedad always managed to make very effective counter attacks, and were able to make Barcelona's defenders quite difficult. Because it is proven, even though in this match Barcelona dominated possession of the ball more, but if we look at the opportunities, Sociedad created more of them. Because in this match Sociedad managed to shoot 14 shots and 6 of them were opportunities that almost resulted in goals. Meanwhile, Barcelona in this match was only able to shoot 11 kicks and none of those 11 kicks were good goal opportunities. Therefore, in this match Barcelona really had difficulty attacking Sociedad's defense. Maybe because Yamal didn't play in this match, it was quite influential for Barcelona's attack line.
It is very true what you say, however you have to see Barcelona's weak point, for me Rapinha is the most efficient flank in Barcelona, they neutralized him, they had to look for play in the center of the field and they couldn't stop the line of center backs, or they took the ball from them or it was offside, in this aspect things can be affected because Barcelona only has its greatest attack there, they should have better attack plans , it is also essential to say that at that time Yamal was not there , so a series of additions that did not suit Barcelona, all that contributes to the results obtained.