To be honest, I've have always believed that it was because of garrosh's encounter with the evil sha gods during pandaria's mists that WOW TBC Gold made his head completely insane and gave him that hulking horrible troll body. Before that even in the Icecrown raid, it is possible to observe that garrosh was smaller and thrall was bigger than him. Also he kind of joined with the iron horde . He grew stronger thanks to those orcs.
He worked hard and grew stronger thanks to his "real iron bros, gangstas".
In addition, I think that Thrall was reserving his words throughout the entire battle because in his mind, he believed that buy Burning Crusade Classic Gold he was the one to blame. He felt the same way until he had a conversation in Korthia with his mom.