As for Lynch, he was the starter for more than 2 1/2 years in Buffalo over Jackson, but if you want to consider that "sitting behind Jackson" I won't try to convince you otherwise.
I'm not saying he sat all the time behind Jackson, but because Jackson was talented too. It influenced the situation where Lynch was, thus making his fantasy production not as good as it could have been if Lynch was in a different situation. So even if Lynch was talented enough to be elite in NFL, there was another guy who was also good.
Touches during 2007-2010
Lynch: 280 + 250 + 120 + 37 = 687
Jackson: 58 + 130 + 237 + 222 = 647
... and I admit that Lynch had problems with life that influenced his touches, but if he would have been in a better situation he would have had more touches.
After he came to Seahawks he has had his best years, not just because he's talent level, but because of the situation.
I'm playing fantasy football and I play to win. I don't claim to see the future or player injuries, but I can see when a talented guy is stuck in a horrible situation so I tend to avoid them.
Freeman is a talented guy, but would I take him if he was the guy behind Peterson? Yes, but the pick would not be as high as it is now. And speaking of Peterson, I rather have his backup now than 4 year ago.