The play was innocent enough, a simple drill in training camp back in August of last year. San Francisco 49ers inside linebacker Chris Borland, then a rookie trying to make an impression on his new employer, made a hit on a teammate in which his own head took the brunt of the blunt force.

โ€œA ding, or what they call getting your bell runโ€ is how Borland described the aftereffects of the hit, symptoms invisible to his teammates and coaches, but acute for the third-round pick out of Wisconsin.

Outwardly, whatever fogginess Borland suffered on that play hardly affected the quality of his rookie season. Borlandโ€™s transition from college to the NFL appeared seamless, as he was the same tackling machine as a 49er that he was as a collegian, notching 108 tackles in 14 games and seemingly establishing himself as a foundational piece in San Francisco for many seasons to come.

There was just one problem โ€” that training camp hit, which Borland thought at the time mildly concussed him. The effects didnโ€™t bother him, but the thought of the effects did. He carried that with him his entire rookie season. Like many fans and fellow players, Borland was keenly aware of the long-term ramifications of concussions. Heโ€™d seen it in the jagged, depression-addled aging of former NFL players like Jim McMahon and Tony Dorsett, and in the suicides of Junior Seau and Dave Duerson.

And quite simply, Borland didnโ€™t want to be them. So in March of this year, at the age of 24, after one great rookie season in the NFL, Borland simply retired, to the shock and likely silent dismay of his outwardly supportive teammates and employer.

Borlandโ€™s decision was far more analytical than impulsive. โ€œIโ€™ve done a lot of research on what Iโ€™ve experienced in my past (two prior concussions before he got to the NFL), projected with what Iโ€™d have to go through to be the linebacker I wanted to be, and to me it wasnโ€™t worth the risk,โ€ Borland said at the time.

For a team that had lost two of the best inside linebackers in football to injury (NaVorro Bowman missed all of 2014 rehabbing a knee) and retirement (Patrick Willis, just days before Borlandโ€™s announcement), Borlandโ€™s decision was devastating, and for the 49ers, the news only continued to get worse as the offseason rolled along.

In June, starting right tackle Anthony Davis, himself like Borland still only in his twenties, announced that he, too, would be departing the 49ers, although he left open the possibility of a return to the team, saying that he needed time to โ€œallow his brain and body to recoup.โ€

In November, Davis suffered a concussion, the first diagnosed concussion of his career, in a game against the New York Giants, after which he spent the next few days in what he described as a โ€œwhite fogโ€ and had difficulty maintaining a conversation. โ€œItโ€™s scary when your brain is not working how itโ€™s supposed to, and the culture of this league is, โ€˜Youโ€™re a big, tough guy,โ€™โ€ Davis said.

Whether permanent or temporary, the retirements of Borland and Davis underscore a bubbling concern for NFL teams โ€” young, informed players who now are not only keenly aware of the long-term effects of concussions and brain disease, but also have options outside of football, either using their college degrees or by having been smart with the money they make their first few seasons in the league.

When they draft players, NFL teams hope those players will be productive members of their franchises for a long time to come. The success rate in finding those players, though, is incredibly low. If an NFL team comes away with three players in a seven-round draft class still with them in four years, thatโ€™s considered a major success. No aspect of the NFL is more imperfect than the drafting of players, which makes the gems that teams are able to find so very valuable.

Chris Borland was one of those guys. In fact, he was as valuable an asset as an NFL team could find โ€” a productive young player on a cheap four-year contract. In a league driven by a salary cap, thereโ€™s no greater commodity than inexpensive, productive labor. Borland was the type of home run that personnel departments spend months of scouting and vetting hours trying to unearth. And come March, just like that, he was gone.

Anthony Davis was a first-round pick back in 2010, a lofty designation that practically implies he must be part of the teamโ€™s future for the next decade, thatโ€™s how critical first-round picks are. So Davisโ€™s need for at least a hiatus is minimally an inconvenience, if not an out-and-out impediment to success.

Suffice it to say, while no 49ers employee is publicly begrudging Borland and Davis their respective decisions, thereโ€™s no way to plan for these developments. They just happened, suddenly and startlingly.

The graveyard, literal and figurative, is unfortunately flush with former NFL players whose careers and lives have been cut short because of brain trauma. Itโ€™s tragic, and fortunately the league is gradually recognizing that. However, there is still a business to run, and building an NFL roster is already a minefield far more fraught with failure than success. Whatโ€™s the likelihood that there will be more Borlands and Davises in the future, and how concerned are NFL front offices about the growth in this early-retirement trend?

โ€œI do think thereโ€™s a ripple effect [from Borlandโ€™s decision] that will resonate over the next decade or so,โ€ Texans draft expert John Harris said. โ€œMost GMs will say that the teamโ€™s process will be able to unearth those players [who could be early retirement candidates], but this is a new world and a new ballgame for them as well.โ€

โ€œTo me, thereโ€™s a way to probe the player, people around him, those close to him and his coaches without having to say, โ€˜Are you scared to play this game because of concussions?โ€™โ€ Harris continued. โ€œItโ€™s delicate, but the GMs that trust themselves and the organization will do it without making a huge ripple.โ€

Borland cited his degree in history from Wisconsin and his desire for further education in outlining his post-career โ€œPlan B,โ€ which intuitively begs the question โ€œWill a playerโ€™s well-roundedness and education (along with the career options that come with that) like Borlandโ€™s actually be a negative when it comes to scouting him?โ€ In other words, will teams want guys who are desperate to play football? Harris doesnโ€™t think that will be the case.

โ€œI donโ€™t think Borland creates an avoidance of a player for being too smart or having gone to a โ€˜smartโ€™ school,โ€ Harris surmised. โ€œTeams will avoid a player that is just โ€˜too smart to be coached.โ€™ But I donโ€™t think just because a player is a good student that it should worry teams at this point.โ€

Davisโ€™s leaving the door open for a return to the NFL after taking time for his body and mind to repair themselves sheds light on a dynamic that many players privately have wished existed for some time โ€” the ability to take a sabbatical or hiatus, if necessary, to heal properly. However, in the Darwinian, testosterone-driven world of professional football, doing so is a virtual impossibility, even though for some it makes perfect sense.

Former Houston Texans nose tackle and current SportsRadio 610 talk show host Seth Payne has said on his show many times that he wishes heโ€™d taken a year off along the way to allow his body to heal from a myriad of different surgeries. Unfortunately, the NFL culture didnโ€™t allow for it.

โ€œFrom a practical standpoint, I always thought it would have been better for my career long-term if Iโ€™d taken a year off to get well,โ€ Payne reflected. โ€œBut I was always concerned about the stigma that came with that. Would teams see me as soft or as a quitter if I stepped away for a period of time?โ€

Payneโ€™s concerns about perception were evident when Borlandโ€™s and Davisโ€™s 49ers teammate, third-year safety Eric Reid, was asked about his two teammatesโ€™ leaving the game and how he assessed his own situation, which includes three concussions in his first two NFL seasons.

When asked if a fourth concussion would lead him to retire, Reid said, โ€œIโ€™m not puttingย a number to it. I will continue to evaluate my own situation. If I have another concussion and I donโ€™t feel like I can play anymore, then Iย wonโ€™t.โ€

Reidโ€™s comments led to headlines insinuating that he, like his teammates, had pondered retirement after multiple concussions. Upon seeing how his comments were interpreted, Reid took to Twitter to clear the air: โ€œJust to be clear, I NEVER SAID, โ€˜Iโ€™ve given some thought to leaving the NFL.โ€™โ€ To Payneโ€™s point, Reidโ€™s tweet hammers home that, unless youโ€™re actually retiring early, the worst thing for a playerโ€™s leverage and teammatesโ€™ perception of him is for everyone to think heโ€™s considering retiring early.

The game of football is inherently a dangerous one to those who play it, well compensated as most of them may be. Players have never been more aware of the risks theyโ€™re taking with their bodies, and down the road this will lead to more players making decisions similar to Borlandโ€™s and Davisโ€™s. It just will.

However, for every Borland and Davis, there will be another few dozen players trying to take their place, happy to get an NFL paycheck, consequences be damned. The survivability of the NFL as a league is not in question, at least not in our lifetime. Too many young men are willing to take the risk, since they have no other avenue to make a living, much less a living that nets them and their families millions of dollars.

Itโ€™s at the micro level of the general manager and NFL personnel departments where this new dynamic plays out so fascinatingly. How do you scout self-aware NFL players who know they are more than just slabs of meat, who know they are more than chess pieces in shoulder pads, who are telling youย everything you want to hear as you scoutย them?

How do you know a college kid is telling you the truth, that his love for the game is unconditional? The 49ers are finding out the hard way โ€” you donโ€™t know.

Chris Borland and Anthony Davis didnโ€™t say these exact words, but the message of their actions is undeniable โ€” the post-career effects of being an NFL player are now being considered by some players as a current-day working condition.

Listen to Sean Pendergast on SportsRadio 610 from 2 to 6 p.m. weekdays. Also follow him on Twitter at twitter.com/SeanCablinasian or email him at sean.pendergast@-cbsradio.com.

Sean Pendergast is a contributing freelance writer who covers Houston area sports daily in the News section, with periodic columns and features, as well. He also hosts the morning drive on SportsRadio...