When the Patriots lost RB Shane Vereen for eight games due to a wrist injury last year, they didn't have "perfect fit" replacement for the role of "passing back" as Brandon Bolden was most often utilized. But they do now in James White, the fourth-round pick from Wisconsin, which is why both Vereen and White are viewed as sure-fire locks to stick in 2014.
The reason Stevan Ridley and Bolden don't garner the same consideration is the possibility that Stephen Houston (undrafted free agent) or Jonas Gray (first-year player) surprise and challenge for a roster spot. That's a long shot, and Bolden brings significant value on special teams, but something that at least warrants consideration. Bolden, after all, made the roster as an undrafted player two years ago.
It's most likely that the Patriots keep four running backs and Houston, Roy Finch and/or Gray finds a spot on the practice squad to add depth.
It's not easy to predict how the Patriots are going to use their running backs week-to-week, but the fact that Reiss sees White as someone who could replace Vereen if injured is pretty big news, especially in PPR leagues. It may be a stretch to give him a roster spot in typical leagues, but he may be a guy to keep in mind if injuries start to creep in on the New England RBs, especially Vereen who missed eight games last year.