Mike you have a good thing but it isn't fool proof.Player don't go up by playing against stronger competition. They pretty much get to the rating they're performing at regardless of their competition.
Let's say I am a unkown player and I only play 500s.
I win at the rate as a 600should as per your Fargo #'s.
Now since the 500s know they don't play well enough to go anywhere how is my Fargo going to go up?
Another thing is a young player who has many games in with other young/lesser players will show a lag in their fargo catching up with them if immersed in the game and their abilities escalate. SVB became a much better player after a year grinding on the road. There is bound to be others.