there was an article about this topic, "RB's changing addresses and how it affects them" or something similar last year on fantasy index's website It did show that Rb's moved to other franchises, actually do quite well with their new teams..
Corey Dillon did well when he left Cincy, Antowain Smith was ok after he left Buff,
TJ has been moved twice, and both times he improved, Lamont Jordan did very well in Oakland last year, OJ Anderson with the 1990 Giants.Heck, even Ahman Green was golden once traded to GB from Seattle..
As for Edge, its probably best to look at Denny Green's history of coaching to find what RB's usually do under him. Robt Smith carried the ball 295 times in 2000 in Minnesota. Much like Az., the 2000 Vikings had a very thin RB corps, with Smith, Kleinsasser, Morrow, and Moe Williams..Similiarly, the Cards are very thin at RB in '06.
the only RB Green has coached that came close to Smith's 295 carries, was Terry Allen, who got 266 carries + 13 tds in 1992, and had to compete with Roger Craig, who carried the ball 105 times. Allen then compiled another 255 carries in 1994..
With the $$ invested in Edge ( and he's partly responsible for the Cards selling out their new stadium), one can make the case that James is going to get plenty of action , somewhere around 300 carries in '06. He is their Crown Jewel, they haven't had a RB like him in a long time, and they will showcase him every chance they get.. Edge is a lock to finish as a top 5 RB , behind only Portis,SA,LT2,LJ, IMHO..
so what if the line is subpar, defenses are going to have to lineup with more nickel & dime packages to defend against the pass, putting smaller DB's on the field and less run stuffing LB's and d-linemen..
the Giants o-line was supposed to be the team's glaring weak spot last year, but it turned out to be their greatest strength, so you never know what happens with the Cards o-line..