There is no DM who can play alongside midfielders as defensively undisciplined as Pogba and Bruno and still hold their own against a top team. It's fine against the bottom half of the table, and Fred especially has shown he can do that already, but against the top 6 we will always need two defensively minded players if we play both Bruno and Pogba together. We have to get away from this idea that we can find a silver bullet in midfield, it is too much work for one player to cover the space they leave.
Firstly, your post implies that Bruno & Pogba do little or no part defensively, which simply isn't true comparative to other players who play their positions.
Secondly, I think we can all agree that when all players are fit, our best XI involves both Bruno & Pogba, Rashford, Greenwood & 1 of Martial & Cavani.
I think we're all also in agreement that neither Fred or McTominay are capable of taking up that extra CM position by themselves - they need each other to really excel.
So, if we continue to play both Fred & McTominay at the same time, it means sacrificing 1 attacking player and/or playing at least 1 player out of position to accommodate this.
Well against "the big 6" that may be all well and good, but we haven't really struggled against the big 6. We've struggled to create chances, score and take advantage of teams that we should've beaten, especially Arsenal (0-0,0-1), Chelsea (0-0,0-0) & Liverpool (0-0). We're better than those 3 teams this season and next season we need to establish ourselves as one of the top 6 teams that is feared, and teams expect to lose against.
But, I have no problem setting up defensively against the top 6. The problem is, that represents only 5 other teams in the league, you can add in Leicester to that equation and make it 6.
How should we set up against the remaining 13 teams in the league? They set themselves up to sit behind the ball and park 2 flanks of players across the pitch against us.
Surely, you're not suggesting we play 2 defensively minded players in both Fred & McTominay, while dropping 1 attacking player and/or moving at least 1 other attacking player out of position, to counter teams that set up like that against us?
Against the top 6 the aim is to not lose the game, the caveat is that we don't create enough chances - but for those occasions, it works.
Against the remaining 13 teams the same thing happens - and thats exactly how we've ended up drawing/losing games where we just couldn't break teams down, and even the games we've won have been far more laborious than necessary because we simply don't have enough playmakers in our team.
We need two attacking midfielders more often than we need two defensive midfielders because we play more teams that we are capable of beating, more often, than we play teams who are on our level or better than us.
There doesn't need to be a 'silver bullet' who does everything, no where have I suggested that. But neither Fred or McTominay can play DM by themselves, and we simply need a DM.