FILE - In this Oct. 7, 2012, file photo, Washington Redskins quarterback Robert Griffin III walks off the field after being hit by Atlanta Falcons defensive end Jonathan Massaquoi durin

 

              FILE - In this Oct. 7, 2012, file photo, Washington Redskins quarterback Robert Griffin III walks off the field after being hit by Atlanta Falcons defensive end Jonathan Massaquoi durin
FILE - In this Oct. 7, 2012, file photo, Washington Redskins quarterback Robert Griffin III walks off the field after being hit by Atlanta Falcons defensive end Jonathan Massaquoi during the second half of an NFL football game in Landover, Md. NFL executives want to change the culture of the league _ and all of football _ to reduce head injuries. (AP Photo/Evan Vucci, File)