The NFL may be a passing league, with quarterbacks dominating fantasy leagues the way top running backs used to, but making sure your team has quality rushers is still key, and finding the Nos. 2-4 backs can sometimes be a crapshoot.

It’s difficult to handicap backup running backs on every team because of a few reasons. For one thing, many teams have as true a split backfield as you can get (i.e., the Panthers with Jonathan Stewart and DeAngelo Wiliams) and some teams still are trying to work out their RB groups (it’s anyone’s guess how carries will be divvied up in San Francisco between Brandon Jacobs, Kendall Hunter and LaMichael James behind Frank Gore).

For the purposes here, the focus is on true No. 2 backs, players that appear most likely to get the second-most carries for their respective clubs but potentially enough to be worthy of a spot in fantasy-football starting lineups. These are the type of backs I look for in fantasy drafts — backs that are clearly No. 2 in the sense that they are the backup, and there is not a third back owners have to worry about. The preseason is key for fantasy owners to see how teams use their reserve backs.

Here's a look at three No. 2 backs worthy of starting spots in your fantasy lineups:

Bills RB C.J. Spiller — Head coach Chan Gailey has made it clear there will be a work-share in the backfield, but Fred Jackson is still expected to get the lion’s share of touches because of his abilities as a blocker and receiver. On the subject of the workload for the Bills' backs, Gailey told the club's website: “I can promise you this, we will not make everybody happy. That will not happen this year. The only thing that will make everybody happy is winning. That’s what the goal is, to come up with plans that incorporate everybody’s abilities that allow us to win. Other than that I can’t predict what’s going to happen as far as percentages for their touches.”