Barcelona's defense has been struggling in recent matches, losing three games in two matches. The team needs to make some tactical changes to improve their performance.

The first match was against Real Betis, where Barcelona conceded four goals in a 4-1 loss. The second match was against Real Madrid, where they lost 2-1 despite having more possession than the visitors. The third match was against Villarreal, where they lost 2-1 again.

These losses have put pressure on Barcelona's manager, Quique Setién, who is under increasing scrutiny from fans and media alike. Setién has made some changes to the team's formation and tactics, but it seems that his players are not adapting well to these changes.

One issue that Barcelona's defenders are facing is the lack of communication between them. The team lacks cohesion and understanding of each other's roles, which can lead to mistakes and defensive errors. This is particularly evident in the way that the back four plays together as a unit, rather than relying on individual skills.

Another issue is the physicality of the opposition teams, especially Real Madrid and Villarreal. Both teams have strong attacking options, and their forwards are able to cause problems for Barcelona's defense. In addition, the opponents are able to get up the pitch quickly and create chances, making it difficult for Barcelona's defenders to keep track of the ball.

To address these issues, Barcelona will need to make some tactical changes. One option could be to adopt a more defensive approach, with less emphasis on attack and more focus on defending. Another option could be to rotate the squad, giving younger or less experienced players more playing time to help develop their skills and confidence.

Overall, while Barcelona's defense is currently struggling, there is still hope for improvement. With the right changes and adjustments, the team may be able to turn things around and regain their form. However, it will take time and effort to achieve this, and it will require the cooperation and hard work of all members of the team.