Fred and McT are natural box to box CMs, a very good fit in a 2 man midfield. Pogba and VdB are not. That's why Fred-McT are chosen regularly, because they are a better fit, not because "they are not good enough to play as the lone DM" or because "Ole is negative by playing 2 DMs". In a 2 man midfield, you hardly ever get a lone DM, and both CMs have to contribute. That's why Pogba and VdB struggle their at times, and McT and Fred are the best options there right now. They are just natural CMs, which we dont have much at our club.