Growing up a University of Illinois fan, Rashard Mendenhall was always one of my favorite college footballers. His 79-yard touchdown run in the 2008 Rose Bowl didn't lead the Fighting Illini to victory over USC, but it foreshadowed what would become of his professional career -- a burst of success and an abrupt end. After six seasons and one Super Bowl championship, "Mendy" called it quits at the age of 26 last weekend. Does his retirement teach us anything about the NFL?

Perception versus reality
Mendenhall's announcement highlighted something that's sweeping pro football: the usage of statistics. From team analytics to fantasy games, today's players are defined by their numerical output much more so than their predecessors. Writing on HuffPo, Mendenhall described how he -- and I expect many other veterans -- view this movement: "The culture of football now is very different from the one I grew up with. When I came up ... the player who gave the ball to the referee after a touchdown was commended; the one who played through injury was tough; the role of the blocking tight end was acknowledged; running backs who picked up blitzing linebackers showed heart; and the story of the game was told through the tape, and not the stats alone."

The last line in particular, echoes a sentiment held by some NFL scouts. A player's on-field intangibles -- many of the things Mendenhall describes -- aren't always in the box score. Just as an assist in basketball doesn't give credit to the pass that set it up, the most widely used metrics don't always measure the true value of football's athletes. While in Pittsburgh, for instance, Mendenhall averaged over 1,000 rushing yards and nearly 10 touchdowns per season between 2009 and 2011 with a mediocre offensive line. This disadvantage doesn't show up on his baseline stats.

Perhaps more important, though, is a realization Mendenhall alludes to, but doesn't declare outright: Fantasy sports, and the elevated level of entertainment present in today's NFL, may not be good for the game. He shares something his older brother, a high school football coach, told him: "These kids don't want to work hard. All they wanna do is look cool, celebrate after plays, and get more followers on Instagram!" League revenues are up, TV ratings are at all-time highs, and nearly two-thirds of Americans watch the sport, but is the spirit of football in danger?

The question can be debated endlessly, and personally, I sympathize with both viewpoints. Regardless of what you believe, though, Mendenhall's retirement -- carried out because he "no longer [wishes] to put [his] body at risk for the sake of entertainment" -- should serve as a reminder of how some professional football players likely feel. I doubt everyone who shares Mendy's sentiment will quit, but the perception that all athletes are cheering on the league's new face simply isn't reality. 

The economics of the running back position
Moral debates aside, Mendenhall's announcement also illustrates the intriguing economics affecting the running back position. According to the NFLPA, the average NFL player remains in the league for a little over three years, and as most empirical research points out, running backs play in fewer career games than all other offensive skill positions.

In an effort to keep ball carriers fresh, NFL teams have begun to adopt dual running-back systems. FanSided discussed the trend last season: "Teams are now moving on from going out and signing that franchise running back and instead are choosing to find backs who can work together and have the production similar to one star runner." 

This mentality -- that the combined output of two running backs is often more efficient, and cheaper, than one -- is more popular now than ever. Last season, six teams gave two running backs at least 150 carries each. Ten years ago, that number was three. Among the league's 32 teams, 14 had two or more running backs with 100-plus carries in 2013, four more than a decade earlier. Mendenhall himself was part of a dual-back system, with rookie Andre Ellington, on the Arizona Cardinals last season. Both hit triple digits in carries, and more importantly, were paid a total of just $2.9 million. The team's top two quarterbacks were paid more than three times that.

The average NFL RB, in fact, is paid 60% less than the average QB. While ball carriers typically face the most hits, the dual-running back system has devalued the position's importance. The impact an individual running back can have on the game is less than it's been in the past, and Mendenhall's career arc -- his 2013 production was about half what it was two years earlier -- is a telling example of this shift in strategy. Even if he did continue playing, it likely would've been at a steep discount to what he's made in the past.

Mendy's career options post-retirement
Through last season, Mendenhall made an estimated $13.5 million in career earnings. Although it's possible he can maintain this level of income, it's unlikely. As I've discussed before, NFL players usually have three post-retirement career options -- broadcaster, head coach, front office executive -- that allow them to continue signing multi-million dollar paychecks. Given that Mendenhall hasn't expressed interest in any of these routes, I don't expect him to pursue them anytime soon.

More likely, he'll explore writing, something he's done throughout his career. Given his level of success on the Huffington Post, a book is possibly in his future, though that offers a decidedly less fruitful career than pro football. According to most estimates, a $250,000 annual take is Mendenhall's ceiling if he pens a best-seller, though given his experience, a book deal is certainly possible. A seven-figure advance would likely be reserved for an A-list athlete like Peyton Manning or Adrian Peterson, but a deal in the six-figure range wouldn't be impossible.

Perhaps the biggest obstacles Mendenhall faces is his lack of major endorsements. He lost his biggest contract -- a sponsorship with Champion -- in 2011 after a series of controversial tweets about the death of Osama Bin Laden. As Forbes' rankings typically indicate, most of the highest-earning retired athletes have lucrative endorsement deals.

The bottom line
There's a lot to take away from Rashard Mendenhall's abrupt retirement, and anytime a player walks away from millions still in his prime, it's worth delving deeper. His feelings about the spirit of football, in particular, are likely shared by many NFL veterans. And in a similar light, the dual-running back system has affected not just Mendenhall, but many of his peers as well.

While I doubt he'll come close to sustaining his level of income post-retirement, something tells me that's just fine with Mendy. Unlike most athletes who play until they cannot, Mendenhall took a more courageous route. For that, he'll always remain one of my favorite players, regardless of whether he's toting a football or a pen.