Schneiderlin is atrocious at the moment, but I don't think replacing him with McCarthy could help.
McCarthy is a poor man's Gana. Two similar players with no creativity is not a good idea.
I take the point that McCarthy is more like Gana. My point was also based around the thinking that if Schneiderlin is not going to offer any creativity, would we not be better off playing (again, if fit) McCarthy because at least he generally does better at stopping the opposition scoring. I think Morgan has been less than directly culpable in many goals conceded this season.
Schneiderlin on his game was and will be better but for the moment something is wrong with him.