Linebacker Chris Borland, who led the San Francisco 49ers in tackles as a rookie last season, is walking away from the NFL at age 24, citing concern of head trauma. Borland told ESPN that he wants to do the best thing for his health, and from research and experience he does not feel that playing is worth the risk. On Monday when he made the announcement of his retirement Borland revealed that his family knew that his rookie season with the 49ers would be his last.

Borland was a third-round draft pick and had 108 tackles for the 49ers last year. He was named defensive player of the week by the NFC after a 13-tackle game against the New York Giants. However, after two diagnosed concussions in 8th grade and high school, and a suspected third last year in training camp, he decided the danger is too great.

Replacing linebacker Patrick Willis midway through an Oct. 13 game in St. Louis, Borland exploded onto the scene with double-digit tackles in every game until Dec. 14. In his final game he sustained an ankle injury that ended his season. Willis announced his own surprising retirement last week.

Borland began reconsidering his football career last August after a collision during practice that he says “got my bell rung.” He decided he did not want “to endure that over and over again over a long period of time.” Today in  follow-up interview he said he might be wrong, and might be able to play 10 years and stay healthy, “however, I just don’t think it’s wise for me.”

Although they respect his decision, General Manager Trent Baalke and CEO Jed York said that Borland’s retirement was unexpected. 49ers radio color analyst Tim Ryan was stunned, trying to make sense of it, saying he found it “a little bit confusing,” but adding “more power to him. He’s a smart guy. I just hope he has no regrets.”

Rep. Bill Pascrell, D-N.J. is the co-chair of a traumatic brain injury congressional task force, and he praised Borland for “a sobering statement,” that puts the issue into perspective. He said the young player clearly understood the risks of what has happened to some former players, who he says are “like vegetables” at 45-50 years of age.

Borland could have continued to receive a $530,000 base salary had he chosen to continue for another year, but he said he did not want to negotiate his health for money. He may continue his education, but meantime is looking for work.