What's not going to help them is making Lukaku a scapegoat.
I won't pretend he played well, and you can ultimately say he cost them the game. But they have a problem with the way they play and there's not much Lukaku can do about it. They're literally firing 60 yard passes at him and expecting him to bring it down, control it, and bring others into play whilst having nothing but City players for company.
In reality, questions need to be asked of Mourinho. More so than before. But they'll deflect it onto Lukaku, just like Mourinho wants and they won't learn anything for it.
Also, signing only 3 players in the summer when you've just finished 6th is risking it as far as a title push is concerned.
We shouldn't be too naive about them. They're 2nd and in most seasons barring this and the last they'd be right in the mix. I won't complain that we're causing them unrest mind :D