McCarthy was called up by England in May for the double-header with Brazil and Republic of Ireland - but he has not been included since.
And Royals vice-captain Morrison feels that McCarthy would still be in Roy Hodgson's squad if he still played in the top-flight.
"The drop in leagues is why, the politics of English football is the reason he's not in the team," said Morrison.
"He's the same keeper he was last season, if not better.
"He shows that week in, week out with the saves he makes.
"I'm surprised he's not in the squad. He hasn't done anything different this year."
Asked if he believes McCarthy is one of the top three English keepers in the country, Morrison said: "100 per cent.
"Obviously there are great keepers out there. You've got Hart, you've got Forster.
"But Alex is up there with them. He is a top-class keeper and I have no doubts he will be England's No.1 in the future."