The hits just keep coming for the San Francisco 49ers. In an offseason that saw the team part ways with head coach Jim Harbaugh, the 49ers also lost running back Frank Gore, receiver Michael Crabtree and guard Mike Iupati to free agency. Then, linebackers Patrick Willis and Chris Borland retired unexpectedly, while defensive end Justin Smith also decided to retire. And now, right tackle Anthony Davis is the latest 49er to suddenly retire.

Davis was a first round pick in the 2011 draft, and went on to start all of the 71 games he played in. For those that may not know, he is only 25 years old.

"After a few years of thought, I've decided it will be best for me to take a year or so away from the NFL. This will be a time for me to allow my brain and body a chance to heal. I know may of you won't understand my decision, that's ok."

"I hope you too have the courage to live your life how you planned it when day dreaming to yourself growing up. Your life is your dream and you have the power to control that dream. I'm simply doing what's best for my body as well as my mental health at this time in my life," Davis said in a statement.

As noted by Shutdown Corner, Davis suffered a concussion on Nov. 16 last year, the symptoms of which lasted a long time. Davis reported seeing "white fog" and experiencing the inability to maintain conversations.

"It's scary when your brain is not working how it's supposed to. And the culture of the league is, "You're a big, tough guy,'" he told the San Jose Mercury news.

According to league sources, Davis will be paying back the unearned portion of his signing bonus amounting to $4.66 million.