A cluster of young NFL players are hanging up their cleats, increasingly citing injuries and, explicitly, the risk of brain trauma.

These voluntary NFL retirements are especially striking because medical advances are helping football players stretch their careers into their late 30s and early 40s. Borland, who led the 49ers in tackles as a rookie, walked away from what could have been a 10-year-plus career and tens of millions of dollars in salary.

He also was being counted on to replace Patrick Willis, the 49ers star linebacker who alsoretired this month — at just 30 years old.Borland’s retirement continues a stunningly awful off-season for the 49ers, who have lost their coach, Willis, and several other key players this year.

And more importantly, it’s another reminder that pro football is being transformed by concussion awareness.

Some of the implications of Borland’s announcement are obvious, but at least one key takeaway is more subtle: Fans aren’t reacting as you might expect to Borland’s early retirement.

Why Borland Quit

Borland hadn’t officially been diagnosed with a concussion in the NFL, but taking a shot to the head in training camp last year — and opting to play through it — raised serious questions that he nursed privately all year.

“I just thought to myself, ‘What am I doing? Is this how I’m going to live my adult life, banging my head, especially with what I’ve learned and knew about the dangers?’” Borland toldESPN’s “Outside the Lines.”

After the season, he consulted with concussion researchers who shared some of the staggering data about the risk of head injuries in pro football. For instance, more than 30% of NFL players end up suffering from Alzheimer’s or dementia — and the frequency of routine, subconcussive blows appears to play a major part.

More than 70 ex-NFL players also have ended up being diagnosed with chronic traumatic encephalopathy, also known as CTE, a progressive neurodegenerative disease that steadily destroys your brain and may lead to violent behavior.

“I’ve thought about what I could accomplish in football, but for me personally, when you read about Mike Webster and Dave Duerson and Ray Easterling, you read all these stories and to be the type of player I want to be in football, I think I’d have to take on some risks that as a person I don’t want to take on,” Borland told ESPN.

I think I read that Chris Borland allegedly wanted to get an advanced degree in physical therapy after his playing days were over. He has always been extremely advanced in his thinking about conditioning and health -- he MADE himself into a candidate for NFL Defensive Rookie of the Year in the weight room and through multiple surgeries. When someone like that, who is widely respected for his intelligence and meticulous preparation, makes a decision to prioritize his long-term health over short-term money and glory... it definitely is something every NFL player is thinking about.

I think you're right that his retirement has made every NFL player think about the health consequences of their careers. 

It was a bold move to walk away from the NFL, especially a week after Patrick Willis did the same thing.

Good for him, but unfortunately the data is far from unclear whether it is "playing football" or "secondary behaviors" that contribute most.  He's definitely not a mathematician. 

Still, if 30% of all football playes end up with Alzheimer's or dementia, those are really bad odds.

He was smart to quit. No amount of money is worth taking on that kind of risk:

http://grantland.com/the-triangle/the-definition-of-tough-how-chris-borland-walked-away-from-his-dream-job/