I believe it was McCarthy's decision himself to go back to Hamilton and get more experience. I know he played in a friendly for Liverpool and even scored a cracker in the game but he probably thought he would be lost in the shuffle at Anfield. Still most young lads would have signed on the dotted line without a moments hesitation when at the club of their favourite player. He showed some maturity in making a decision to stay at Hamilton.
He does remind me of a young Gerrard though. Looks kinda similiar and even has the same body type.