Colorado was an NFL feeder school in the 1970s and Missouri was often good (in 1976 5/8 finished in the top 20). It was like a lot of P5's now. Very good at the top, not-so-good at the very bottom, but still a good conference
I'm afraid you've chosen a bad example. In fact, I'm afraid you won't find a good example, because people care about titles for high quality conferences.