Jake Plummer left the NFL well before he had to. Getty Images

[This week, Rick Reilly writes about John Lynch, and his struggles to leave the NFL. Some do, however, and willingly.]

It's not a situation Drew Rosenhaus comes across very often.

"When a player in good health tells me that he wants to retire?" he asks the interviewer, clarifying the question. "Well…"

According to the NFL Players Association's official web-site, the average length of an NFL career is about three and a half seasons. The site lectures, "Although there are some exceptional players who have long careers that extend 10 or twelve seasons and beyond, most players only stay active for about three seasons. Players leave the game because of injury, self-induced retirement, or being cut by the team."

Self-induced retirement?

It sounds like made-up, corporate-speak (kind of like "downsizing"), mostly because it almost never happens. A player who can claim he decided to "self-induce" his way out of the NFL is about as rare as the blade of grass who can make a habit of dodging the John Deere.

For years, the standard-bearer for "too soon" was Jim Brown, the Browns icon who walked away from the game after nine years, with every rushing record in tow. Brown, however, had an acting career on the side—an extra income. Over the past few years, however, players such as Barry Sanders, Robert Smith and more recently Jake Plummer and Dante Culpepper have walked away when there was still some health to spare, and checks to be made.

Emphasis on the checks. Rosenhaus says that's the key concern for his clients.

"If a guy says he wants to walk away from the game, I go through a discussion with them where I make sure that I discuss what a blessing it is to have the ability to play in the NFL, and to make the kind of money that NFL players can make," he says. "We do talk about how hard it is, outside of football, to make a living in general."

If Rosenhaus sounds like an agent who only cares about his 4%, he's quick to emphasize that he's never tried to talk a player he felt was dead-set on leaving that the game was his best or only option.

"My concern first is with the guy as an individual, his family, his goals. We go to great lengths to help prepare a guy who is ready to retire to do what ever it is he wants to pursue after the game," says Rosenhaus.

Asked to name a specific case of a player he felt may have called it quits too soon, Rosenhaus declines.

"That's a personal thing," he says.

He also admits it's a rare one. Players know that their careers will usually be short, and they are told to plan ahead. Yet because they know their careers have such a looming expiration date, most of their energy is directed toward staying in the game. Self-preservation usually wins out over future-preparation. In the case of Plummer, the money had already been made. "He still loved the games and the guys, but it was all the stuff in-between," says a friend. "It's the grind." He was thus free to work on his foundation, or play more of his other notable passion, handball.

When Brown played, a six-figure contract was a rarity. Even in the current game, contracts are always front-loaded. A deal announced at $30 million typically offers far less than half that total in guaranteed money, and those deals are rare to begin with. So players play til they can't, and sometimes a bit longer.

When the New York Times tells the story of a player such as Andre Waters, whose repeated concussions led to a deterioration of his mind, and ultimately, most believe, his suicide, that point is driven home further.

The body is a terrible thing to waste, but so are those scant possible years of service.

The NFLPA site concludes, "while players may make more money than most people, they are only making it for an average of three and a half years. To make sure they are successful in the future, players must invest their money well and make plans for another career when they can no longer play football."

No kidding.