Overall Barcelona defense is still strengthened by players who looked charming guarding Barcelona defense area last season. Villarreal is a strong club, they also play at their own headquarters, in my opinion it is very natural that Villarreal has the ambition to win matches in front of their supporters.
The three goals scored against Barcelona show how much Villarreal wants to secure full points, but Barcelona are much better than those who managed to score four goals. I don't really focus on Barcelona defense, it's normal for them to concede three goals because Villarreal has a good attack. Barcelona managed to keep a clean sheet in the previous two matches, conceding three goals is not a big problem, but Barcelona players must be able to close the movements of opponents who want to penetrate their defensive area.
Barcelona made a move at the end of this transfer market, borrowing Jao Canselo from Man City with a permanent purchase option. Barca's defense looked porous in the match against Villarreal, the addition of this versatile defender is expected to patch up Barca's defense.
However, what caught the most attention after that game was Barca wonderkids Lamine Yamal, many predicted to be Messi's successor.