Football Outsiders has a really tremendous article looking at trends in rush distribution amongst backs. The piece is very long, so I'd recommend reading it as I will definitely not get close to covering it all. In fact, I really can't start clipping in quotes without providing a good bit of context. Read the article. Also, there are some trend graphs that you'll want to take a look at. Did I mention that you should endeavor to read the piece in its entirety?
Here are the general concepts of the piece, so now you are all set to go read the article.
- Since the NFL started changing rules to benefit the passing game, the total number of carries per team per game has remained roughly stable.
- Since 1980, lead backs have always received (on average) more than half of their respective team's total carries.
- As teams began to specialize the roles of the fullback and halfback, the feature back emerged.
- The workhorse running back predominated through the 2000's (think about Priest Holmes, LT, Shaun Alexander, etc.).
- The last two seasons (2007, 2008) have seen the lead back receive less carries as teams spread the carries around .
- The dual-RB system has been on the rise since 1980 with almost exponential growth.
- Finally, the recent trend away from a single workhorse has happened twice before, although at lesser magnitudes.
Now go read the article.
We've seen success out of teams with both single elite rushers (Shaun Alexander again), as well as the success of the Giants committee and the Chris Johnson / LenDale White duo (amongst other tandems). While the dynamic duo sets lead to fresher legs and lower injury risk, it's hard to keep a guy like Adrian Peterson off the field in favor of anyone. As a fan, what do you prefer? Do you like the notion of having one man to rely on always, or do you feel more comfortable with a mix of players bringing more specialization to the backfield?