I was a big fan of this combo in first half of the season (when our game was completely reliant on Bruno, and we needed them at the base), but since then a lot have changed.
It seems we've learned how to use fullbacks in attack, and with Pogba finally finding his feet in attacking position it feels like we just need the midfield duo to provide defensive stability.
Fred is not a defensive midfielder, he has poor positional sense, average tackling ability and easily brushed off the ball.
He can't be the last man in front of the defense. What he does well is he keeps the ball moving and has super engine, meaning he is really good supporting midfielder.
McTominay... I still don't think he is a midfielder. In theory he has all the tools but it just doesn't feel natural for him. The main problem is lack of awareness, meaning he spends too much time on the ball just to make a simple pass in the end (which is often intercepted). It's clear he likes to drop to the defense and to the right, he feels very uncomfortable in the middle.
IMO we should really be looking for a replacement for McTominay - a proper DM is what we need. Then we could line up like that:
Back 4
DM
(holding position)
Fred
(buzzing around)
RW Bruno Pogba
CF
It doesn't feel like we need attacking contribution from our midfielders, what we need them to do is to support the front 4 and cover for fullbacks and Centre backs.
Leicester play similar way with Ndidi (holding position and covering for defenders joining attack) and Tielemans (supporting both attack and defense). I like their balance, and since we clearly have far superior players in wide areas and in attack, I believe we could replicate that easily which would benefit us greatly. In the future we might upgrade on Fred, but I doubt it'll be this summer as we probably have bigger issues.
They both deserve huge credit for this season though. McTominay for his goals and Fred for his general play (BTW I think he's playing to maximum of his ability).
I agree with the statement that midfield is not our biggest issue, but at the same time it seems easy to improve.