For running backs I look at it this way.......
1st - What was the individual able to accomplish in their career.
2nd - What kind of team did they have around them to enable the quality of their career.
3rd - What could that person do AFTER they got the ball (Speed, break tackles, run routes, block, etc)
Perfect example is Emmitt.
1st - Easy, all time most yards, thus, ranks high
2nd - All stars from end to end and the biggest O-line ever (at the time). Sure makes it easier to run when the holes are 3 yards wide. To me, this takes away from Emmitt but was a plus to Barry because of his bad O-line. That monster line Dallas had could have made any running back look great.
3rd - Emmitt could do just about everything well. So I rank him high. I don't think the company I put him in from my other post puts him in bad company.
Given "my criteria", Emmitt would rank lower than the other runners I listed. But I must say, I really don't know much about the lines and teams that Sayers and Brown played with.