Having not seen Davis play much, if at all, at CAM, do we know that?
I jumped off the Davis hype train and burned my ticket a long time ago, so take my opinion with a grain of salt, but regardless of where he's played in the midfield I don't think he's shown the skill set to succeed as a CAM. He's a "safety first" player, which is fine for a #6, not for #10. He's never shown the ability to pick out a creative, incisive, positive pass. He has never shown the ability to beat players on the dribble. He doesn't shoot any more often or more efficiently than our other guys. I think people saw his one goal against LA last year and hyped him up to be way more of an attacking threat than he actually is.
One of the terms Matt Doyle throws around pretty often is a player's "gravitational pull". The best playmakers are threatening enough to make defenders move out of position to stop them, and skilled enough to play through that pressure to spring teammates who now have space to operate in. I put Davis in the same boat as Muyl - they have no gravitational pull because when given acres of space they still don't even attempt to make a dangerous play, so defenders barely have to pay attention to them.
Duka, for better or worse, at least tries shit.