Don't know if we really should apply lessons from our golden 4-4-2 days (with the double pivot) in todays football. I am with you, I don't think, FDJ should be seen as some sort of DM - I also don't have a good feeling about him next to Fred as two defensive minded B2B players. The B2B role in the PL requires more energy, I don't think FDJ has that. And while I am sure, he will be aweseome with once we have the ball, I feel we would be laughably open once we lose it. Fred is a chaos player, you put him close to opposition buildup mechanism (be that balls to FBs or a pivotal player in midfield or even in defense) and let him work, but he has no positional awareness what so ever as he is so ball focussed.
The setup yesterday didn't do him any favors as he wasn't exactly deployed next to McTom but rather behind McTom and Eriksen. But, as soooo fecking often, the distances grew larger and larger making it impossible to play through the center at some point. That being said - he wasn't good yesterday, no question about it.