The figure that explains the French striker's bad streak is easily exemplified by the fact that he has not yet completed a shot between the three posts of a goal outside of the Camp Nou.
Indeed, even though the Antoine Griezmann has now had four chances (Bilbao, Pamplona, Dortmund, and Granada) to prove himself outside of the home turf, he has not yet managed to live up to the high expectations which followed him to the Catalan city. With Messi and Suarez out in some of those matches, that is, with the focus more on him, his rough patch has become more apparent and therefore he's received more of the blame than some of his counterparts. He came to shine for the team, but has been unable to do so when it has been his turn to take charge.
Griezmann has been in all six official games so far, although he has only 'played' in two. His double against Betis and an assist to Arturo Vidal made him essential in that win, and although he got no goals against Valencia, he was an active element in attack and hit the post several times.
The worst, moreover, is that his shine has been fading more and more as matches come and go, to the point of making almost no difference whatsoever against Granada in Los Cármenes. What's more, Ansu Fati has already been a lot more helpful.
Hs only excuse, perhaps, is the fact that Valverde has not let him settle into a single position just yet, which means the Frenchman does not yet have one comfortable position in the field.
However, the Frenchman's quality was expected to be above that. He was not necessarily expected to become Barcelona's top scorer, but both the fans and the board were probably expetcing him to become more central in the creation of chances.
Even Ernesto Valverde himself has publicly spoken about his bad spell, and Barça's environment is being very critical of Griezmann.