NFL general managers gather their smartest people each winter to analyze rosters, assess options and formulate a plan for the offseason marketplace. In 2014, at least, they made quick work of the running back position.

By now it's no surprise to hear or read about the plummeting value of running backs. No one wants to pay them premium salaries or even spend a first-round draft pick on one. To this conversation, I'd like to add an obvious and clear representation for why.

The information in the fancy line graph, courtesy of ESPN Stats & Information, is similar to the type of analysis NFL teams use. It shows, in pretty stark terms, how running back production drops off after the age of 27. (Hat tip to ESPN.com editor Brett Longdin for generating the graph.)

The red line represents all running backs who have played at least four NFL seasons since 2001, with a minimum average of 75 carries per season. Overall, we see their careers peak at age 27. Afterward, their rushing totals drop by 15 percent in one year, 25 percent in two and almost 40 by the time they are 30.

Most decision-makers -- whether their background was in scouting, accounting or anything in between -- saw that trend as a bad investment. As with any business, they reserve premium contracts for projected growth in production, not a decline.

For comparison's sake, the graph also includes the receiver position (in blue, minimum average of 50 receptions over the same time period). You'll see some fluctuations, but even at age 31, the composite receiver produced a near-identical yardage total as he did at age 27. In other words, it's reasonable to expect a high-level performance into a receiver's early 30s.

Running backs get no such benefit of the doubt, nor should they from a strict business sense. Even Minnesota Vikings tailback Adrian Peterson, one of the league's best players at any position, contributed to the curve at age 28 last season. It's true that he had the fifth-most rushing yards (1,266) in the NFL, but he also missed two games and overall fell 40 percent from his 2,097-yard effort in 2012.

That line graph, along with a season that produced its fewest total league-wide rushing yards (57,795) in six seasons, led us to the eye-opening 2014 offseason. Keep in mind that age 27 is the essential point where most players, under the current collective bargaining agreement, become free agents for the first time. At their first opportunity for a payday, the league already views them to be beyond their prime.

As of this week, teams have 177 running backs under contract. Of that group, 128 (72 percent) are 26 or younger. I counted only eight runners over the age of 29. Meanwhile, there was an obvious link between the handful of mid-20s running backs who did receive multiyear contracts this spring: None have been four-year feature backs.

The Detroit Lions will pay Joique Bell (27) the eighth-highest salary for a running back in 2014 ($4.3 million). He has 248 career carries, an average of 62 per season.

Toby Gerhart (27) will receive $4 million from the Jacksonville Jaguars. He has averaged 69 carries per season. Donald Brown (26) also will get $4 million from the San Diego Chargers after totaling 551 carries in five seasons, while Ben Tate (25) will get $3.25 million from the Cleveland Browns after totaling 421 carries in four seasons.

And that's pretty much the list. What about Knowshon Moreno, who is 26 but has 845 career rushes? He got a one-year deal from the Miami Dolphins. Maurice Jones-Drew? He's 29 and has 1,804 career carries. His contract with the Oakland Raiders guarantees him $1.2 million for 2014. He'll earn $2.5 million, assuming he makes the team.

It's fair to expect the trend to continue expanding to the draft. NFL teams didn't draft a single running back in the first round in 2013, and at the moment, ESPN's Scouts Inc. doesn't project one to be selected in the first round this year, either. (Their highest-rated runner, Ohio State's Carlos Hyde, has a mid-second round grade .)

The message is clear: Running backs of this generation picked, well, the wrong generation to be running backs. Teams want them young, cheap and fresh -- and the data makes it difficult to argue their point.