With regards to Fernandes, he is a bit of an anomaly by all accounts.
He was always a very good player in Portugal. He has a really good knack of shooting, crossing, very decent creative player, and most of all a really good amount of drive and work ethic. Players like that rarely drop below their standard. So unfortunately he can't be downed by the United curse. At least not yet...
United have been clever enough to put him at the centre of everything. Not only does every attack go through him, but he takes penalties and set pieces too. He's bound to rack up good stats with their team of giants. And as I say he's consistently at his level.
Of course he's not elite level, nor is he playing for an elite team. Which means a really good side can keep him and the rest of United quiet, and it's unlikely he'll ever pull the proverbial rabbit out of the hat à la De Bruyne. It's noticeable how generally ineffective he is against the top sides this season. But against the dross they play on a weekly basis for the most part, he's more than good enough.
He's a great flat-track bully. For a team with ambitions of top 4 and regular semi-final appearances, he's great for them.
But the fact he's not quite an elite player and yet he's leagues above the rest of their team is telling about the rest of their squad.