The Roman Empire ended up becoming so vast and big that the Roman people weren't able to be adequately protected by the army. Also with it being so big they weren't able to get direct orders from the capital (for lack of a better term) so they were easier to rebel. However what acclimated to the fall of the Roman empire was the fact that they were overthrown by a Germanic leader. So the main reason distance affected the people were because they had such a stretched out army that they couldn't help quick enough. I'm sorry if this isn't the answer you were looking for or if I was too late.
