That really isn't surprising. I like Kemba as a player and he seems like a good guy, but there isn't exactly a booming market for 6-foot tall combo guards. The one thing that he does have above other prospects in that category is that he is actually an excellent rebounder, but I'm not sure that warrants a pick in the Top 8.
I remember seeing after one of the workouts, Jazz I believe? Where it was Kemba vs Jimmer, some people were saying that Kemba had a hard time staying in front of Jimmer on the defensive end. After that I saw him falling past the Kings on updated mock drafts.