San Francisco 49ers' Chris Borland retiring from NFL
Health fears lead young San Francisco 49ers linebacker Chris
22 NFL players who retired early, from Gronk to Barry Sanders
Chris Borland retires from 49ers after one year due to fears over
Is Chris Borland's retirement the beginning of the end for the NFL
Chris Borland Retiring Due To Head Injury Concerns : r/nfl
Chris Borland, Fearing for Health, Retires From the 49ers. At 24
San Francisco 49ers Linebacker Retires at 24 Over Head-Trauma Fears
Wesley Walker, former Jets great, wishes he had foresight to