‘“When you’re face to face with a guy, you’re not just face to face,” said Trevor Matich, an ESPN analyst who played center and long snapper for 12 NFL seasons from 1985 to ’96. “You smash your face back into his, and it’s a sudden stop for both of you. And your face stops, but what’s on your face keeps going, and so particles of spit, sweat, tears, blood if you’re bleeding, whatever. As a lineman, your potential for what is being called a ‘viral load’ close to you is high.”’