What’s with those bobblehead NFL helmets?

If you’ve been watching the NFL this season, you’ve probably noticed that a few dozen players have pretty big heads. Not in the diva sense, but literally. Take Chris Olave, the New Orleans Saints wide receiver. He wears a Guardian Cap, a padded cover on his helmet for added protection against head trauma. The trade-off is that it makes him look like he just nabbed a mushroom power-up in Super Mario. Olave, who suffered four concussions in his first three NFL seasons, has made peac...