Is it really hard to just give some credit to the man at some point without feeling the need to qualify it with endless "but" statements? He won a header in the box from a corner which caused problems for the Wolfsburg defence, resulting in a goal. You can pick apart virtually any goal to find ways that it 'should' have been defended, ultimately it doesnt matter unless you can call it a true defensive 'howler' - which I dont think it was in this case.
As far as "why are we playing him in midfield" goes, that is a question to ask LVG, and not something I would really be pegging Fellaini with as a criticism. LVG knows what to expect from Fellaini and gives him a role in the team accordingly.
Going back to performance, you need to understand and appreciate that when Fellaini is receiving the ball it is more often than not with his back to goal. He is also usually tightly marked. Not an excuse per-se, but rather that when he is in a position to play a forward pass I think Fellaini normally does so with average success. However compared with other midfielders he is less likely to be in a position to make a forward pass, as he is (presumably by instruction) playing further up the pitch and with his back to goal.
I agree, positioning is not one of Fellaini's strengths and one of the reasons I think it is risky to play him in a midfield pair. That said, I think it was obvious tonight that the instruction was for Fellaini to play further up the pitch and have Schweinsteiger (and then Carrick) in a deeper role. I agree with you here though, and it is why his best performances for us came last season in the more advanced CM role alongside Herrera, with Carrick in a holding role behind. That 4-3-3 system gave both Herrera and Fellaini license to roam forward without too much need for positional discipline, and it brought out the best in both of them I think.