When you play high level like this everybody knows the others best players, ie Nekro's Cass, Mollica's Skarner, Fdru's Warwick, etc. After you do all the targeted bans, it leaves open other good players that normally do very well in public matches.
I used to watch a lot of the tournaments with CLG and every team that played them would ban Nidalee and Cho Gath because they were HSGG's best players. Normally, those wouldn't be top bans but it would allow players on the team to get Orianna (when she was a top pick), Zilean, etc.
So Kass keeps slipping by because he is good, but not the best pick for the team over some of their other champions.
I enjoyed watching the tournament last night, I wish I knew these had been going on because I would've been watching them every week. Nice to see some streaming of Dominion. Hopefully, it brings more players into the mix.