Now that the Buffalo Bills have set their 53-man roster, we'll break it down, position by position:
Talent: A. Spiller looks primed to emerge as one of the NFL's premier running backs and has the skills to back it up. While he is on the smaller side at 5-foot-11 and 200 pounds, Spiller has top-end speed and change of direction ability. Jackson, while he is in the later stages of his career, has some bulk (216 pounds) and power left in his game. Few NFL teams can match the talent the Bills have at this position.
Depth: A-. When looking at some of the other top rushers around the league -- Adrian Peterson, Doug Martin, and Arian Foster -- none have a player of Jackson's caliber as a second option. The one knock against this unit would be its lack of another young player to develop. The Bills had Kendall Gaskins (rookie) and Zach Brown (first-year) in training camp, but neither stood out. Choice, whose contract expires after this season, is an upgradeable piece.
Reliability: B-. The biggest concern for the Bills lies with Spiller. If he becomes the "featured" back in the Bills' offense, as he is expected to be, can he hold up over the full season? Spiller will need to prove that he is durable, even when taking 250 or more carries in a season. Likewise, Jackson is 32 years old and hasn't played a full season since 2010. Losing either would put some stress on the other.