I mean, the dude who wrote that is Albanian so that explains a lot. He's been bashing him even when he was scoring regularly at the beginning. It's always sad when you have to deal with such people who have bias against someone based on their nationality.
As far as Dusan goes, not concerned too much personally. It's always difficult to make a mid-season switch. New team. New coach. New system. And of course at Juve, much higher expectations than at Fiorentina. But the system change is definitely the biggest "issue" I believe. Going from free-flowing attacking system at Fiorentina to Allegri's idea of football is a big jump.... for better or worse
You can tell that he's the first one who's frustrated at the way things have been going recently but I do believe that the next season, after he goes through the full summer preparations with the team, will be the genuine one in order to judge him and his value to the team.