If they wanted to stick to the threshold of 10, Fox really ought to have commissioned its own series of polls, ranking candidates and looking at their popularity relative to other candidates. If they polled a sampling of head to head matchups, they'd have a MUCH better understanding of who deserves to be in the debate and who doesn't.
My guess for who'd make it if the criteria was that they were leading in the most head-to-head matchups against the other candidates (not necessarily in this order):
1 Bush
2 Walker
3 Paul
4 Carson
5 Rubio
6 Huckabee
7 Cruz
8 Christie
9 Perry
10 Kasich
So a candidate that has 20% of the Pubs absolutely adoring him, and 40% absolutely hating him, would not be in the debate? It seems that you are focusing on the like to dislike ratio or something. While it might be a good proxy as to whom might get the nomination, it's tough to justify excluding someone from the debate who has a significant chunk of support. Perhaps the debate venue might change the mind of some of the candidate's detractors. Yes, I know, that is not going to happen with Trump, but dealing with tough cases like Trump (so that he is excluded), can lead to bad/unfair rules as it were overall - and cause a lot of resentment among some Pub primary voters.
I should have said at the top that I think limiting it to 10 candidates is a stupid, arbitrary rule. If there's 17 candidates, find a way to get 17 candidates on a stage. But if they're looking for the most substance, and were determined to stick to 10 candidates, my suggestions was that they pass it through a filter where they might recognize which candidates actually have a chance of winning. That is, if Trump dropped out of the race, who would his support filter down to? If Bush dropped out, who would his go to? Etc.
