Realistically speaking we are likely going to be running with a two man midfield throughout the season.
We have Pogba, Herrera, Fellaini, and Bastian as our box to box/CM midfield options, and Carrick and Schneiderlin as our holding midfielders\ deep lying playmakers.
Unfortunately I don't think we can continue with all four of those options at CM and we are probably going to need to cut our losses with at a least two of those players. Bastian is likely going to be one seeing as he is much slower and way too injury prone. Fellaini is a serviceable backup option , seeing as he has had two slightly above average seasons with us, but Herrera offers a lot more overall as a player.