The 19-year old Scotland youth captain made the move from Aberdeen this week and McCarthy, who left Hamilton to become a Latics player in 2009, feels he will adapt to life in the Premier League with ease.
"I had to wait six months to get a chance and coming down from Scotland was a bit tough for me because I was moving away from home, but I've come in and settled really well and I love it here," McCarthy told the club's official website.
"It's different from the Scottish game because the tempo is a lot higher and when you come here you have to compete against big-name players.
"I've said to Fraser already just to take his time and he knows it will take time.
"He's a good lad and after meeting him for the first time he seems like the sort of person who will settle in really well here.
"He's done well with us today but once he's training with us more he'll really kick on.
"I've always thought he is a great talent and obviously I'm delighted that he is here and I'm sure he'll come in and do well because he's looking sharp in training.
"Aberdeen started a couple of weeks earlier than us so he has got that little bit extra coming in and he's looking really good."