http://www.gamesas.com/topic/1476083-who-benefited-most-from-the-wgc/?p=23086919
Them not receiving Leyawiin comes from the novels. Supposedly Mede said they were never able to have the city acknowledge his rule or something. Someone else who's read them can confirm for me. But no, I don't have evidence and can't claim it as fact until someone does.
As for the Alduin comment, Tullius getting lucky and ambushing Ulfric isn't relevant, what is is that he was able to gain so much support at all, and after he escaped, Tullius wasn't able to reproduce the same result. That pretty much proves it was a fluke and not a showing of Imperials and their ability to suppress internal problems. If he could reproduce that result, it would be different.
It's like a nerd on the basketball team about to get a lucky three point shot, but by some act of god, an earthquake shakes the rim and he misses, and he can't do it again. Then having his teammates say he's an excellent shot.