Big 12: Eric Vann
Posted by ESPN.com's Tim Griffin
It might be the most endangered species this side of the American bison.
True workhorse running backs are disappearing across the nation, but particularly in the Big 12.
It's a marked contrast from the past where many Big 12 teams would rely on one major back to account for much of its running production.
Even the expansion of spread offenses can't be blamed entirely for this predicament. If anything, the overabundance of passing attacks should make it easier for one back to dominate carries because most teams are utilizing fewer running plays than ever before.
Here's an indication of how skewed the statistics were last season in the Big 12. Only four backs accounted for at least 40 percent of their team's rushing totals.
Texas Tech's Shannon Woods led all Big 12 backs last season with 44.5 percent of his team's carries -- 141 totes among Texas Tech's 317 rushing attempts.That total is the smallest for a leader in the Big 12 in the conference's history.
Consider only four years ago that nine Big 12 backs accounted for 40 percent of their team's carries in 2004 and seven backs that season topped 50 percent of their team's running plays.
But in today's Big 12, coaches are opting to predominantly use a rotation of backs. Teams like Nebraska (Quentin Castille and Roy Helu Jr.), Oklahoma (DeMarco Murray and Chris Brown) and Texas (Vondrell McGee, Cody Johnson, Fozzy Whittaker and freshman Chris Whaley) all are expected to rotate carries in 2009.
Here's a look at how those numbers have changed during the Big 12's history.