Thing about the Big 12, is that they don't really put guys in the NFL (relative to the other BCS conferences). Now that doesn't necessarily translate into inferior college programs (relative to the other BCS conferences), but in this sport where not even close to everybody plays everybody, you never really know, so I do think the sparse NFL talent in that conference does affect the overall quality of play.
Here's a screenshot of some research I did last year, where the database I was working w/ is all players who were on an NFL roster or practice squad in the year 2006. I've made everything pertaining to the Big 12 in bold red so you can see:
The "PPT" stat below is what those conferences are sorted by, and that means "AVG NFL Players per Big 12 Team," that gives you an idea on average, just how much NFL quality talent is on a Big 12 playing field on a given day. Obviously this data is a year old and doesn't include anybody in the Big 12 today, but this stuff doesn't change much year to year.