Barkley had an amazing basketball IQ. You don't succeed as a 6'5" power forward without one, no matter how athletic you are. He had excellent instincts, and terrific court vision.
Much like when he was a player, Charles simply likes to say things for shock / entertainment value. He gets paid because people react to what he says. He could say something nuanced and balanced, but who wants to hear that? People tune in because Charles makes bold, definitive, often ridiculous statements.
Also, Barkley wasn't the only one thinking the Cavs were a better team. He just proclaimed it louder than most others.