Gustaf being real big is such a delusion.
The guy is tall, so is Diabate. He is tall, slender, and has t-rex arms. He isn't that big at all. He is tall.
I think the dude is pretty big. Look how thick he looks here:
Gus might be tall but he isn't exactly skinny. The dude has a big bone structure as you can see from his hips in these pictures, besides being fairly muscular. Very strong core.