There were ten people on the stage. WAy too many.
There should be three tiers. Just like minor leagues, AA, AAA and MLB
I would go for one-on-one and rotating opponents with the same questions. That would scare hell out of a non-principled, inarticulate candidate. Consistency from one debate to another would be critical. I would not have problems with the use of social media. Allow the people to select the debate topics and questions. Have a time keeper instead of a moderator or have neither.