http://espn.go.com/espn/otl/story/_/id/12496480/san-francisco-49ers-linebacker-chris-borland-retires-head-injury-concerns
Now this, this is big news. And I don't think Borland will be the last in the next few seasons, far from it. NFL's got a serious problem; it's put up or shut up time.
(And to answer Kendrick's question - if we don't get an RB like Gurley or Gordon in the first round, I'll be sad)