Pogba has had great games at United without Carrick. He had the luxury of playing with Pirlo for a couple of years, and now Carrick for a couple of weeks, but there's no definitive evidence to suggest he needs that to perform.
Marchisio, for one, isn't really like that pair and Pogba has looked perfectly fine alongside players like Vidal, Khedira and Matuidi elsewhere.
We aren't going to be playing with "some lump" at the base either. I'd imagine Mourinho wants an athletic, physical ball winner that can also help initiate attacks. Makelele, Cambiasso, Motta, Essien, Matic and Khedira have all played regularly under Mourinho in the past, none of whom play like carbon copies of Carrick.
I've got no idea if this Monaco lad is up to much, but if he's a good defensive midfielder that can sit infront of defence then I'm sure he'll be a welcome addition.