Maybe Anduin was at first only travelling to Icecrown, because he finally told Talia what happened to her father and she wanted to see it herself, then the whole 'ripping apart the skybox'-thing happened, Anduin and Talia got thrown into the Shadowlands, Bolvar got rescued out of Icecrown by the Ebon Blade and .... then the rest of the pre-patch takes place. What we can read in those lines is the aftermath of that and one part of the story about why we are going over to the SL (after we discover it's not Bolvar unleashing the Scourge in the pre-patch).