Today, during a World Cup game between Morocco and Iran, Moroccan winger Nordin Amrabat suffered a wicked head injury when he collided with an opponent. After he went down, a team trainer tried to revive him by slapping his face—a move decried by athletes and followers online. But despite the frequency of those kinds of injuries in soccer, you won’t see many international pros wearing gear that might prevent a concussion—reinforced headbands.