that's where the signing on fee comes in though. McCarthy was signed in the last hours of the window on a hastily put together contract. Both sides wanted the move to go ahead so it was decided that he'd sign and there would be a proper 'increased' contract once he established himself in the first team. Depending on who you believe he's on £25,000-£38,000 a week currently in comparison to Barry/Cleveley who are on £50,000-£75,000 again depending on who you believe.
James is just after the original contract adjustment he was promised (unless you disagree as the club obviously do that he's established himself in the first team).