If you thought Sajam/James Chen and/or Seth Killian/Mike Ross was bad, then you're in for a world of disappointment. These guys are honestly, in my opinion, four of the best casters in the business. Ultra David is also very much like these guys, but he opted to be part of the crowd during top 8 this year instead of casting (probably just missed the feeling). All of these guys have upped the quality of the games that I've watched and, to top it off, they actually play the game so they understand it. Most of the time whenever one slips up, the other person is there to immediately correct the mistake. And as for advertising chairs, well...they have a responsibility as they are sponsored by Vertigear along with many other companies.
Casters have so many responsibilities, especially when it comes to Top 8 of a tournament--not to mention it being the largest fighting game tournament of the year. The fact that these guys are able to commentate so well and calmly (most of the time) in front of a crowd this huge is a testament to how long they've been doing this.
Also, I'm sad that there wasn't really a lot of character diversity in Top 8. 3 Nash and 2 Chuns. Then the last 3 were Vega, Mika, and Ken. Like, people talk about how balanced this game is all the time, but my goodness does professional play make these character look MUCH better than the rest of the cast.