I think wins play a big role, and pergaps RPI. I dropped from a n A+ prestige to an A with a 1st round NT exit. It was a down year as I only made the tournament on the basis of a CT win and was 20-10 on the season. The season prior, i was a top 15 team and made the sweet 16. This tells me that just making the tourney is less important than having a solid season.
Or, just exactly what Al was saying, only with an anecdotal reference to use.