49ers’ Chris Borland, a Top N.F.L. Rookie, Will Retire Because of Safety Concerns
Borland, 24, is the youngest and most promising of a number of players to leave the league this off-season as concern over brain injuries roils the sport.
Borland, 24, is the youngest and most promising of a number of players to leave the league this off-season as concern over brain injuries roils the sport.
