It's harder to win on the road, this you have to be a better team to do it.
Why do you think Kelly has so many wins at home, but when he goes on the road...ehh, not so much. If Kelly were playing the kind of schedules Holtz was he would be struggling at home as well, but these schedules are just watered down enough that he can win most of them at home (unless a big boy comes to town) then when he goes on the road he can still at least competitive (unless we visit a big boy).