It's the old apples and oranges dilemma, how do you compare a back who ran 40 years ago, to one who's still going? You have to look at a lot of factors, like number of games played, the talent level in the league, and of course, how much better they were than their peers. You can also throw in that championship factor, but it doesn't carry nearly as much weight as it does with QB's, because runners aren't the generals on the field, they're just the artillery. For simplicity's sake, the player is listed with the team he spent the most time with.