Even the power in his jab (as well as the speed) of it has a visible impact on his opponent. I think it was the impact of the jab to the chest early in the fight that seem to shake Stephen Fulton enough that it made him unable or unwilling to carry out his own fight plan. Like Mike Tyson used to say. "everyone has a plan untill they get hit" and I think that's exactly what happened to Fulton once he felt the power in Inoue's jab to his chest..
Inoue destroyed Fulton's body with that jab downstairs. It's like he couldn't miss with it because Fulton was terrified of the shots upstairs. It was a glorious exhibit of body punishment.