I don't understand #nfl anymore. If RB can't lower head what do they do, take on tackler with chest?

title="http://profootballtalk.nbcsports.com/2013/03/14/nfl-may-prevent-runners-from-lowering-their-heads-into-tacklers/">profootballtalk.nbcsports.com/2013/03/14/nfl…

#c'monman

— Marco Rubio (@marcorubio) March 15, 2013