I don't think it's about "who is next to Martinez" because this D has become much more about the hybrid LB/S Pettine has been using all season. The D took a dive after they lost Raven Greene who was playing very well in that role, and then has recently started to improve again because Sullivan has been playing so well in that same spot. Of course also Kenny is back but the pass defense has been better behind him too. Employing that hybrid backer puts the spotlight on Martinez as the only true ILB. He'll have fewer responsibilities in coverage but it also puts more emphasis on his position when the offense is able to isolate him. He is serviceable and reliable in run support but can be taken advantage of by a good OC. You'd really like to see someone more athletic there but we can win with him if the rest of the D keeps improving the way it has.
They'll be without Cook but it will be interesting to see how MIN tries to attack the middle of the field, aka Blake.