They are still a young team, which explains their current situation. Barcelona haven't stabilised yet and progressing with such a situation is difficult. Barca fans may feel uncertain about this team, especially if they look at Barca back-line.
Their problem is that they haven't found Pique's replacement. Pique is already 35 years old and his physique has declined. Even Pique always has a hard time facing a striker who can run quickly. I think Xavi should start thinking about the central defender. I think he should be brave to start the rotation,for example by installing Kounde as the starting line up. Because Xavi is carrying a mission of improvement and he deserves to give more playing time to the younger defenders.