On paper, a midfield trio of Schneiderlin - Herrera - Fellaini has it all (almost) in terms of creativity, attacking and defending; and would be strong enough against any team in the league. I think Mou can make those trio to work.
I couldn't disagree more actually.
Having a balanced midfield isn't a case of having one good at defending, one good at attacking and one good at creating. It's about having players with a balance of all three who compliment each other.
Take Herrera for example, he's not exactly got a pass and move partner there. Schneiderlin isn't a water carrier, he needs a partner to sit alongside him occasionally and Fellaini isn't really a partner to anyone in midfield. He does very little through the middle, his best play comes from feeding off a deep pass and linking up with wide players. Pass wide, attack central.
Herrera and Schneiderlin could work with a player who facilitates them doing a little bit more. Either a partner in crime around the attacking third for Herrera or a player who let's Schneiderlin get forward a bit more and break the play up around the middle rather than deep. That's what he had in Wanayama at Southampton. At the moment he's trying to do what he did at Southampton from deep and it's a bit ugly and a bit risky. Put a proper defensive midfielder behind him and let him do his work further forward and we'll see the best of him.
Schneiderlin, Herrera and Fellaini isn't a case of blending 3 different skillsets and covering all bases, it's an ugly mishmash of styles who don't compliment each other one bit.