Why was Rexxar demoted?

Rexxar has not been demoted. He has moved on into the Outlands. He has his reasons and if you manage to visit him in the Thunderlord Stronghold in Blade's Edge Mountains, you can find out more. I don't want to reveal too much in case others are looking to find out his story.

His replacement I'm sure will do the best he can to fill Rexxar's shoes but we all know that no one can BE Rexxar but Rexxar.