You're making my point better than me!
Khadra can play off a striker, he did so for Blackburn on occasion I believe. I was under the impression McAtee was a AMC that would play in a 4-2-1-2 type formation. That or out wide, either as a winger or as a Foden like wide forward.
So, why have we signed him? Seems odd if he's just a sub to come on. Given we're told he had lots of offers and presumably City want him playing regularly, which is the best way to develop any young player.
Hecky is playing 3 CMs. We have Fleck, Doyle, Norwood who would naturally play those role. Berge wants to but looks a bit of a liability on the defensive side and much better when he's further forward. Osborn will say it's his preferred position, but again hasn't looked good enough there.
The we have one player (Ndiaye) playing off a striker. Khadra can do that role, although I don't think it suits him. As you say, I don't think McAtee can. Plus, our record signing is on the bench and we saw him partner McBurnie (who you're not dropping now). We also have Sharp. Against Preston, he was prepared to play Ndiaye deeper, although that didn't really work until Doyle came on. Which would make me think that if Ndiaye needed a rest or was injured his preference would be McBurnie and Brewster upfront.
When McAtee has played in the LCM role, he's looked like a boy against men. Doesn't seem to have the strength of the tackling/marking/tracking ability to play it. His tackling style is risky, to say the least. By all accounts, this is not his position or one which he's played anywhere else.
Hence, I think what I was trying to say is that his signing makes no real sense, thus far, to me anyway. I can't believe City would let us sign him as an impact sub.