I was watching an old Green Bay vs Chicago game and then I saw Walter Payton. The guy would literally run over people. It's not that he was running through arm tackles. He engaged the tackler and sized up defenders and ran over them. OJ Simpson could sort of do this. Eric Dickerson could do it a little, but it was mostly Walter Payton and Earl Campbell.
When you look today the only 2 dominant power backs are Peterson and Lynch. But they don't actually physically engage defenders today. Peterson never does it. Lynch rarely does it. When I think of power in today's NFL I just think of guys you can't reroute. Like Peterson will throw a stiff arm and he just can't be rerouted. He doesn't go shoulder to shoulder and just mash them over like Payton and Campbell.