Buyer Beware on Aging Running Backs in Fantasy Football 2015

There's a changing of the guard underway at the running back position in fantasy football. Young ball-carriers like Le'Veon Bell of the Pittsburgh Steelers and Eddie Lacy of the Green Bay Packers are staking their claims as the kings of the fantasy mountain.

Granted, aging backs like Matt Forte of the Chicago Bears, Adrian Peterson of the Minnesota Vikings and Marshawn Lynch of the Seattle Seahawks are still being selected early in drafts. According to the average draft position data at Fantasy Pros, all three backs are being selected in the first round of both 10- and 12-team leagues. Lynch and Forte were top-five fantasy performers in both standard and PPR scoring systems a year ago.

However, as well as those running backs performed last year, before using a first-round pick on any of these players in 2015, savvy fantasy owners would be well-advised to step back, take a deep breath and consider a couple of very important issues.

Because for these backs, the Latin phrase Caveat Emptor rings true.

"Let the buyer beware."

Given how well Forte and Lynch played last year, and that Peterson was a top-10 fantasy asset at his position two years ago before losing nearly the entire 2014 campaign to a nasty child abuse scandal, some may be asking, "What's the problem?"

Well, as it turns out there are two.

Age

There may not be a position in the NFL where how many candles are on a player's birthday cake looms as large as at running back. In recent years we've seen numerous NFL teams swap out veteran options at the position for younger, cheaper players.

That RB ageism extends to the realm of fantasy football as well—and with good reason.

Back in 2012, Chase Stuart of Football Perspective conducted a study of 36 NFL running backs in an effort to gauge when those backs' production falls off the proverbial cliff. Stuart's study concluded that those backs generally peaked by age 27, and that by the age of 32 the wheels often came off altogether:

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This group of running backs peaked at age 26, and had a four-year prime from ages 24 to 27. Among all running backs (in the study), there was a very steady decline from age 26 to age 31 and then a sharper decline at age 32.

There is no one age when all running backs drop off, or even an age where the majority of running backs drop off. That said, by the end of their age 29 season (or, if you prefer, by the time they hit 30), half of the running backs in this study were essentially washed up.

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In 2014, ESPN's Kevin Seifert conducted a similar study that was even less flattering to the 10 percent off at Denny's set. A study Peterson was part of:

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(Of) all running backs who have played at least four NFL seasons since 2001, with a minimum average of 75 carries per season, 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.

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Are there exceptions to the rule? Of course. There always are. But when a pair of studies both reach a very similar conclusion it's a good bet that there's some substance to that conclusion. And the conclusion that these studies reached is that for running backs, 27 is as good as it gets. And turning 30? That's no bueno.

Peterson turned 30 on March 21. Forte will join him on December 10. Lynch is the baby of the bunch, having turned 29 on April 22.

But all three are, at least historically speaking, on what should be the downslope of their NFL careers.

Workload

Of course, age isn't the only factor to consider when trying to discern when a tailback's production will decline. There's also the matter of the physical toll inherent to the position.

Most fantasy fanatics are at least vaguely aware of "The Curse of 370." In a nutshell, the overwhelming majority of running backs who have carried the ball more than 370 times in a season saw their production drop sharply the following year.

It's a big part of the reason why DeMarco Murray of the Philadelphia Eagles, who carried the ball 392 times for the Dallas Cowboys a year ago, is falling into the second round this season despite leading the NFL with 1,845 rushing yards in 2014.

However, there's more to it than just one huge single-season workload. There's also the cumulative effect of years of toting the rock.

In an effort to discern how much work is too much work, Joseph Juan of NumberFire examined the careers of every NFL back over the past 15 seasons who accumulated over 2,000 career carries.

Juan's study showed that 1,800 appears to be the number no one wants to see:

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Using historical data, we've provided some predictability in the high stakes game of betting on running back longevity. It appears as though players plummet in productivity and value soon after the season they cross the 1,800-carry mark. Only time will tell if the high-profile names on our list of candidates will fall to this seemingly inevitable fate this upcoming season, but if there's one thing we've learned, its that the fall off the cliff is a swift and fast one.

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That list Juan mentioned?

Forte, Lynch and Peterson are all on it.

Mind you, this isn't to say that these running backs are all totally and irrevocably doomed to burst into flames the first time they touch the football in 2015.

After all, it wasn't that long ago that Peterson responded to concerns about his surgically-repaired knee by reeling off 2,097 rushing yards in 2012.

Forte's age and career workload didn't stop ESPN's Christopher Harris from pulling the trigger on Forte with the eighth overall pick in a recent experts' draft:

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Are there warning signs? Absolutely: Forte turns 30 in December and only produced three 100-yard rushing games in '14. But he topped 100 scrimmage yards nine times (tied for fifth among RBs), and found the end zone 10 times (tied for seventh). Sure, departed coach Marc Trestman loves throwing to RBs, leading Forte to set a record for RB receptions, but I'm guessing new coordinator Adam Gase saw that game film. Plus, John Fox's Chicago Bears are likely to go run-heavier to protect mercurial Jay Cutler. I didn't see anything on tape from Forte that makes me think he's lost his fastball.

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And Lynch? Well, he hasn't finished outside the top five at his position in standard scoring fantasy leagues since 2010, and I'm willing to go out on a limb and say that the Seahawks are going to run the ball a fair amount in 2015.

The problem is it doesn't take that much for a first-round pick to disappoint. A few missed games. Fewer touches as teams attempt to keep their aging bell cows from breaking down. A combination of the two.

Is it possible that all three of these aging running backs will spit in Father Time's eye, scoff at the idea there's too many miles on their tires and once again post elite fantasy numbers? Sure.

However, it's also very possible that at least one of these players is going to drop off significantly in 2015, and figuring out which one is the fantasy football equivalent of Russian roulette.

So choose carefully, oh fantasy drafter.

Or your season could be over before it starts.

Gary Davenport is an NFL analyst at Bleacher Report and a member of the Fantasy Sports Writers Association and the Pro Football Writers of America. You can follow Gary on Twitter at @IDPSharks.