Why can't 4 of the best 9 teams come from the non-BCS? LSUtootnanny is considering not only winning percentage, but who the teams played in a Ratings Percentage Index (RPI) style ranking.
While not every team with talent is going to live up to its potential and not every BCS conference team is well-coached, there are going to be enough BCS conference teams who have good enough coaching to make use of the talent they have to make that an impossible scenario. The numbers I posted in my minor conference vs. BCS conference thread should be enough to show that such is the case.
There are some very good coaches at non-BCS schools, but they eventually graduate to the big-time where they will have more talent and money with which to work. A minor conference team will rise up and have a great year from time-to-time, but not 4 of the top 9 or 6 of the top 18.
Miami-Ohio has a legit claim to Top 10 status, though based more on what their opponents did than what they themselves did. I don't necessarily think they were one of the 10 best teams this season, but I do believe they had one of the 10 best seasons. They had the best season for a minor conference team since probably BYU in 1984.
Boise St has had Top 25 caliber seasons the last two years, though that has been exclusively feeding on minor conference teams. I'm not sure they would have done that well even in MWC or C-USA. They played one BCS conference team in 2003 and lost to a very mediocre Oregon St team. In 2002, they lost to 9-5 Arkansas 31-7. I think each of the seasons was good enough to warrant inclusion in the Top 25, but, again, I do not believe they were one of the 25 best teams either season. No way did they have a Top 10 season either year.
TCU in the Top 10 or even the Top 25 is a joke. They played two Top 40 teams all year and lost both games. They struggled mightily against quite a few very bad teams. Had they played a BCS conference schedule they probably wouldn't have even had a winning season.
A case can be made for Utah at the bottom of the Top 25, but not Top 10, and that's only because this was a year in which the gap between BCS and non-BCS was smaller than normal. Even there, they lost to a Texas A&M team who went 0-8 against BCS conference teams with winning records. Still, they did have quality wins over Cal and Oregon.
A case can also be made for Bowling Green at the bottom of the Top 25. Their road win at Purdue was impressive. Of course, that's really the extent of their Top 25 credentials. Still, in a season like 2003, that's arguably enough.
There's no doubt that minor conference teams had more claims to Top 25 status this year than probably any year in the past 20-25. Very few BCS teams played with any degree of consistency. Things drop off substantially past the Top 10 and past the top 16 or so, you're really having to take some questionable teams to fill out a Top 25. On average, however, there aren't any legit Top 10 teams amongst the minor conferences and only two or three have any real arguments for inclusion in the Top 25.