This might change quite a bit with the addition of Gundogan who brings in all the experience necessary to compete in the Champions League. He is also a few years younger although Barcelona isn't really adding strength to their squad. Busquets left, Gundogan joined. They are now considering a swap of de Jong for Silva from Manchester City. This would mean de Jong is gone, Silva is added. There is still no significant change that makes the team fundamentally better. They have a good center line from the offense with Lewandowski via Gundogan in the midfield and ter Stegen in the back. But is it quite the same as it was last season despite some names that will have changed when the new season starts.
Of course, they don't have a football player like Messi who changed everything by himself, but I think the midfield of the Barcelona football team consists of really good players. However, there are also rumors that Xavi wants to sign Thiago Alcantara. If Barcelona wants to create an assertive team both in the European cups and in the league next season, they should increase the competition within the team with better quality players. Therefore, it would be a good choice for them to sign Thiago Alcantara after Ilkay Gundogan and Inigo Martinez.