There are certain positions in the NFL in which having one standout player is enough. Finding a quarterback is really hard, for instance, so when a team finds a great one it builds the offense around him.
Running back is different -- no team relies exclusively on just one. David Johnson was a workhorse last season, handling 76.8 percent of all carries by Cardinals players, the most in the league. But there were still more than 100 carries that went to other Cardinals in 2016.
The point? Having multiple backs is not a luxury in the NFL. It's a necessity.
With that in mind, we're ranking the NFL's best backfield tandems from 1 to 32 for the second season, taking into account usage, skill set and production.
A team that relies heavily on a solo back might not rank as high on this list as you might suspect -- but that's not an indictment of the starter, rather that the team widely relies so heavily on him that the backup is less of a factor. (Think Andy Reid has any reservations about feeding Kareem Hunt as much as he has so far? No way.)
Again, this is about backfield pairings, not the best individual backs.
Note: This list excludes running backs who are currently nursing long-term injuries, like Johnson and Danny Woodhead.
Devonta Freeman and Tevin Coleman: While many backfields feature players who can adeptly handle more specific roles, Freeman and Coleman are a rare one-two punch that can each play in any offensive situation. They're excellent pass-catchers and solid runners between the tackles, and each is effective in the red area. Together they account for 42.8 percent of the offense's yards from scrimmage. Freeman, who has rushed for a league-leading five touchdowns this season, is among the game's best.
Leonard Fournette and Chris Ivory: It's important that personnel aligns with the approach of the team. The Jaguars don't want to spread things out on offense and chip away through the air. They want to wear you out, to have defensive linemen looking for a substitution and linebackers feeling like they are the ones who have been tackled, not doing the tackling. With Fournette and Ivory, Jacksonville has the kind of backfield defenses hate to see for four quarters -- especially when you consider 52.27 percent of the Jags' offensive plays are on the ground, the second-highest rate in the league.