Chris Borland, the former San Francisco 49ers linebacker who abruptly retired from the NFL following a promising rookie season, predicted recently that the trend of "early" retirements by NFL players not interested in dealing with the physical and mental after-effects of a decade-long professional football career, would only increase as we came to better understand head injuries, concussions and the long-term effects of chronic traumatic encephalopathy (CTE).

It seems Borland has already been proven right, as Buffalo Bills linebacker A.J. Tarpley announced his retirement from the NFL on Thursday, citing concern over concussions.

"The only thing comforting about not knowing this play would be the last of my career, is knowing that I never took a second for granted," Tarpley wrote on his Instagram profile.

"After months of introspection, I am retiring from football. I suffered the 3rd and 4th concussions of my career this past season and I am walking away from the game I love to preserve my future health.

"This decision is the hardest I've made yet but after much research and contemplation I believe it's what is best for me going forward."

Tarpley's agent, Ryan Downey, later confirmed his client's decision to retire.

Borland's 2014 retirement was shocking because of its suddenness and the short duration of his career. The decision just this offseason by players like Calvin Johnson, Marshawn Lynch, Jerod Mayo and Husain Abdullah to call it quits on the NFL after impressive careers that could easily have been extended, were less shocking, even if they did grab just as many, if not more headlines.

Guys like Johnson and Lynch left a lot of money on the table to preserve their health. Borland and Tarpley walked away from a career that could have potentially earned them millions before it every really got underway.

Tarpley, like Borland, played just one season in the NFL. After starring at Stanford, Tarpley landed with the Bills as an undrafted free agent, appearing in 14 games in 2015, collecting 8 tackles, one sack and two interceptions.

He also suffered two concussions during the season and clearly felt there was more to be lost by continuing his football career than to be gained via that earning power.

Tarpley may not be a big name, but it's a troubling trend for the league, especially when combined with the words of owners like Jerry Jones and Jim Irsay who have done the best they can to distort the link between football and concussions.