Essentially, no one is capable of scoring while he is on the ice, and defenses cannot let him have his way offensively since he's been out there for eight out of the Rangers 15 goals this season, an excellent passer and puck awareness, he's always been a great two-way player.
Hopefully a second Norris trophy is on the cards for Fox. He's playing like a worthy recipient for it this early in the season, and if he keeps this up, he might soon be running away with it.