I was just looking at some NextGen stats and i'm kind of seeing this in his weekly route charts. Maybe someone can dig a little bit deeper into this, but this is what I have from my preliminary assessment:
Since week 1, Hopkins is average approximately 3 routes per game over 10+ yards. In week 1, he had approximately 8 routes of 10+ yards that he ran. In weeks 13-17 in 2018, he averaged about 7 routes per game over 10+ yards.
Look at Fuller's route chart the last two weeks:
The only other thing that I can see is that they are not moving him all over the field like they did last year. When they move him on the left, right and slot, he seems to blow-up.