Another point this argument is making, is there is a HUGE income difference between RBs and WRs, and production wise, the compensation is not fair at all. The difference in the positions is, RBs usually come into the league ready to start. Rookies have little trouble acclimating to the game, since they've done nothing but run through holes and take handoffs for the previous 6-8 years. They also have the young mileage in HS and college of being the guy on the team with the most touches.
It's no surprise then, when they hit the league running, their bodies burn out quickly. I think 3-5 years is the average for an NFL RB. This means they usually don't get a second contract worth their touches. So you have a few RBs that are elite for 8 to 10 years, whereas the WR position is much less intense on their bodies. WRs will get 2 or 3 contracts in their career, each one escalating in value. RBs rarely ever see a 3rd contract. This is what boosts the value contracts by position for RBs vs WRs.
I don't think it's fair for the league to chew up and spit out RBs, when they get little in the way of compensation, as a whole. They touch the ball on the team more than any player but the QB, yet are paid one of the lowest salaries by position on offense. I understand the mechanism that makes them paid lower, but vs their productivity, it shouldn't be close and they are being taken advantage of.