49ers Linebacker Chris Borland Retires Over Injury Concerns

You can still count on two hands how many players walked away from a pro football career with more good days likely ahead of them than behind.That's why Chris Borland's decision to retire at age 24, after a great rookie season with the 49ers and a near-guaranteed huge payday down the line, sent shockwaves rippling across the NFL. The announcement came within days of retirements by 20-somethings Jason Worilds, Jake Locker, Cortland Finnegan and 30-year-old perennial Pro Bowl 49ers linebacker Patrick Willis, whose spot Borland was expected to fill.Each of those players cited different reasons for calling it quits. Only Borland, who suffered a concussion in training camp last fall but covered it up in a bid to win a spot on the field, tied his departure directly to the continuing risk of brain injury."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 said Monday on ESPN's "Outside the Lines.''But more surprising, and perhaps even more unsettling for the league's long-term prospects, was the reaction from fellow players and the game's...