"He's working hard but I've picked sides without him because I felt the players in form needed to play.
"I thought he did well when he came on at Man City. Benni has been an outstanding player for us and has been for 18 months.
"He's been lacking a bit of form but I just sense he is getting back to somewhere near where he needs to be and he's more likely to be involved."
Chelsea are among the clubs who have shown interest in McCarthy recently but Hughes insists there are no plans to sell him.
He added: "There is no chance of that because the price I would get for Benni wouldn't allow me to replace him with a player of the same ability.
"I would find it very difficult to justify letting him go under any circumstances."