I'll keep my comments short for this one since I can be long-winded sometimes.
Because of the Portis situation, I wanted to see what has happened historically when RBs change teams. I looked at any RB since 1983 who was a 1,000 yard rusher the year immediately before he changed teams. I could've included a RB who was a 1,000 yard rusher any year before he changed teams, but I thought that might to some skewed data since the gap between the 1,000 yard season and the team change might be pretty large. I choose the 1,000 yard mark for obvious reasons. It's the baseline for which we consider a RB at least average. Also, anyone not achieving 1,000 yards probably played less than 12 games that season.
http://kingghidorah.is-a-geek.net/Fanta ... change.htm
16 times since 1983 have running backs changed years following a 1,000 yard season. 6 of the 16 saw an improvement in their total fantasy points, 10 of the 16 saw a decline. 1 of the 10 who declined in fantasy points did so only marginally (9%), so for purposes of fantasy, you might consider that a success in a draft since that's probably less than the average player decline from season to season.
Notes about the spreadsheet:
1. Age is the age they started playing for their new team.
2. I prorated the points for a 16 game season. This doesn't seem to have any noticable effect since most of them played at least a 13 game season before and after the switch.
3. Carries is the # of carries they totalled in any 1,000 yard season before the switch. I thought knowing this might show some trends, but it's somewhat meaningless since I don't have years spent on the previous team with it and it might be misleading.
4. Earnest Jackson earns the distinction of being the only player to appear on the list twice, once as a gain, once as a loss.
5. I left Charger RB Gary Anderson off the list. He rushed for over 1,000 yards in 1988 then didn't play again until 1990. I don't know what happened to him (I'm assuming major injury), but I didn't want to bias the stats.
6. I think there is a definite pattern to the players who increased and decreased in the successive season, but I'll let you draw your own conclusions.
7. Yes those comments were short. For me at least.