Could Calvin Johnson walk away from football?

On July 27, 1999, the Wichita Eagle received a letter through their fax machine. It was from Barry Sanders, who delivered the news to his hometown paper that he would retire from professional football after ten seasons with the Detroit Lions. His letter was succinct, short and to the point in regards to why he sought to leave the brutal bloody spectacle beloved every Sunday by sports fans: "The reason I am retiring is simple: My desire to exit the game is greater than my desire to remain in it. I have searched my heart through and through and feel comfortable with this decision."

In an instant, the Lions said goodbye to one of their biggest stars in the modern era. He left with the Lions still chasing glory, still short of Walter Payton's rushing record, still healthy and in apparent control of his senses. Sanders was not breaking down physically (yet he played a position that brutalized his body nearly every time he was on the field), nor was there an emotional tug coming from another avenue of life. After a time, he simply decided that he had finally had his fill of football.

Now, another Lion might walk that same line and retire after years of violent competition. Rumors surrounded Calvin Johnson before the offseason even began. There were many coming to the conclusion that the nine-year veteran would no longer wear the blue and silver; he would seek another team, or the Lions would trade him or cut him in an effort to rebuild and get out from underneath his contract; a contract that dictates a $24 million cap hit next year alone. But Wednesday brought a new thought: he might simply walk away from the game completely.

The rumors ostensibly began on Tuesday with Terry Foster, radio host for 97.1 WXYT-FM in Detroit. On the station's blog, Foster made the hypothesis that Calvin Johnson could follow Barry Sanders into retirement early. He freely admits that he has no inside sources close to or personal contact with Calvin Johnson on the matter, but he points out two pieces of evidence from the end of the Bears game: first, Calvin Johnson took the game ball following his touchdown in that season finale. It was not a milestone achievement for Calvin Johnson, being his 83rd touchdown pass. This alone warrants a little suspicion, but it could also just be said that it was his final touchdown of the season and that might be enough. But Foster also pointed towards something a little more primal when it came to his suspicions: the weariness he believes is in Calvin Johnson's statements when he talks about his future, the non-committal in regards to certain questions where Megatron not only deflected the notion of returning to the Lions, but of his own health.

On Wednesday, Dave Birkett of the Detroit Free Press expanded upon this. Citing sources close to Calvin Johnson (which the Free Press calls an "ex-teammate" in the breaking news segment but is not listed in the article), Birkett puts forth that wear and tear -- the overall injuries sustained in the course of playing football -- might be the driving force for Calvin Johnson to consider retirement.

Not long after, Calvin Johnson and the Detroit Lions issued statements.

Here's the full Calvin statement pic.twitter.com/EXQwp3mU5f

— Dave Birkett (@davebirkett) January 6, 2016

The translation offers much to the imagination but likewise a promise for an answer in the future. But these are not the words of a man looking for a trade necessarily, nor are the Lions in a position to find a suitor.

Calvin Johnson's contract takes him through 2019. The specifics are grim, if you are speaking strictly from a realpolitik stance that you would take if you were the Lions front office. The dead cap ensures that his contract will remain a problem through 2016 and still on the books in 2017, if more manageable. It remains unattractive for many teams who would want a wide receiver, certainly not one at Calvin Johnson's age after a season where his performance dramatically declined.

But for all the talk of Sunday possibly being Johnson's last game in a Lions uniform, most of that came from a place where Calvin Johnson would continue to play football. It did not come from the belief that the 30-year old receiver would simply walk away from the game.

And yet, it's very possible.

Lifespans in the NFL are short and brutish, and the average football fan's perspective on that reality is warped and twisted by the very fact that the most outstanding football players succeed the lifespans of their fellows numerous times over as they become gleaming stars for a team or journeymen that bounce from one town to another. Talent plays the critical role, but a more ominous piece of natural selection is in play: health.

Football hurts, constantly. Injuries that do not result in concussions or season- and/or career-ending catastrophes are swept under the rug as being part of the game, which they are, but these still accumulate on the body. One needs only read an excerpt from the ESPN The Magazine feature on Peyton Manning, which simply feels painful in reading.

And Calvin Johnson has had pain. Even in a position that relies far more on speed and agility, Calvin is no stranger to the physical brutality of football. His very playing style is predicated on that. Gifted with a 6'5" and muscles on muscles, Calvin Johnson has bullied and dominated corners and safeties and linebackers in the process of making catches. He has gone up time and time again for a jump ball hurled into the heavens by Matthew Stafford and beaten two, three defenders to come down with it. He's bruised and battered his way into the endzone. To make a basketball analogy, Calvin Johnson is the power forward or center who goes in and bangs in the post on nearly every drive.

Darryl Tapp would be "very surprised" if CJ retired after nine seasons: "At the same time, his body’s taken a whole lot over those 9 years."

— Josh Katzenstein (@jkatzenstein) January 6, 2016

That adds up. That puts miles on a body that only has so many and cannot just receive new tires at the dealership. Calvin Johnson has suffered injuries upon injuries, and while he did not miss time this year as he did in 2014, he was repeatedly marked questionable on injury reports and questions arose as to how much pain and damage he was playing through. The body can only deal with so much.

As the body begins to betray, one's mind might look upon the game and reevaluate decisions. It's a violent, dangerous sport that's played. Fans might wonder why anyone would chose a life other than this, but it's not their bodies that are put on the line in the NFL. It's not their career decisions being hung in that balance. There's only so many costs one wishes to endure in the name of a game that sees men stretchered off the field every Sunday.

And this may just be it for Calvin Johnson. Like Barry Sanders before him, he may simply want to walk away and find purpose beyond football; his desire to exit now stronger than his desire to remain. We'll know soon enough.