People are already Habingering gundogans deal to be one of the best for Barcelona. It speaks more about how we see football. Gundogan is indeed a vibrant player,  who still has a lot to offer even at that age. But the question is, will he fit into xavi/ Barcelona's style of play??
Gundogan didn't play often for Pep Guardiola ( for important reasons like age factor) gradually,  the club adapted to De Bruyn which then withdrew attention from Gundogan. But Gundogan was still doing well when ever he is featured in a game.  This was because he enjoys Man City's pattern as a team. And he's she didn't affect him due to this pattern. factors like oo much Dependency/ pressure will be high on him in Barcelona and I doubt he will yield the outcome has expects.