Ken: I'm not sure if you're basing that on the poll that Probst took at the reunion (where everyone except Edgardo, Michelle, and Dreamz said they would have voted for Yau), but that can't be used as evidence of Yau's status as a jury threat. I think you can easily argue that Yau was only the biggest jury threat precisely because Yau was betrayed by Dreamz, and it's impossible for Yau to make the F3 if Dreamz betrays him anyway. Also, one of the few criticisms that the jury levelled at Earl was that he betrayed Yau, which he obviously doesn't have to do if Dreamz gives up immunity. Even after Yau became the martyr of Fiji, Edgardo and Michelle would've voted for Earl for sure and Dreamz would've voted for either Earl or Cassandra. I doubt that Rocky/Mookie/Alex/Lisi are locked votes for Yau in any situation in which Yau makes the F3. In a Earl/Yau/Cassandra F3, I think Yau gets Stacy/Boo and Earl gets Horsemen + Michelle, and then Earl only needs to pick up one of Rocky/Lisi/Dreamz (if Dreamz is the sole vote for Cassandra, his tiebreaker vote would go to Earl anyway).
Kos: What moves did Yau-Man make? The early boots on Ravu were standard, and NuMoto never went to TC after the tribe swap. The Michelle boot was out of their control thanks to the twist, the Edgardo boot was Stacy's idea, and the Mookie and Alex boots were predictably formulaic. After that Yau used his idol at F6 (for which he obviously deserves credit), Boo left at F5 as the only remaining player outside Earl/Yau's alliance, and then Yau got screwed by Dreamz.
Think about who was in Earl/Yau's alliance at any point in the game. Michelle was closer to Earl than to Yau. Cassandra said in an interview (
http://tv.ign.com/articles/789/789452p2.html) that she never even considered voting Earl out, and Dreamz was obviously closer to Earl than to Yau. The only people who was closer to Yau was Stacy, whom Yau targetted at F6, and Boo, whom he voted out directly afterwards. Earl was unlucky that Michelle, one of his closest allies, was taken out by a twist, and yet he was still in by far the best position in the game after that anyway. You could've happily taken Earl vs. the field at any point after the merge.