You can also look at rankings from the point of view of where you have to be to have a serious shot of making it to "near the top," which to me would start with the Elite 8 and even more the Final Four. There are a number of teams (any from the SEC and B10) that do regularly get into Top 10 and Top 20 territory but for whom the E8 has been the ceiling during the last 6 years when UConn has been running to four NCs. But at what point is just being ranked of little value to getting to the E8 or FF?
The tipping point might be a little lower down than what we would think, especially if we get too fixated on years like 2012 when incredibly the E8 teams were all 1-2 seeds and FF teams were all 1 seeds. It would be nearly impossible to imagine a #7 seed and #8 seed meeting in the NC game, as with the men last year, whose rankings often get totally crazily chewed up by March Madness. The women's Tournament is sometimes called "predictable," but I would say that it follows reasonably close to the rankings but with some major differences, which is what I would expect from decently done rankings. Some say they love the wildness of the men's tournament, and sure, but you also have to say that the rankings then aren't worth much. You can't have it both ways.
For WCBB during the last 6 Tournaments, eight teams have made it to the E8 who were ranked outside the Top 10. The ones not advancing from there included 28th ranked Purdue and 19th ranked ASU from 2009, 20th ranked Gonzaga from 2011, 14th ranked Georgia in 2013, and 12th ranked UNC in 2014. The three who fought through to the FF included 16th ranked Baylor in 2010, 16th ranked Louisville in 2013, and 11th ranked MD in 2014. Louisville also went to the NC game from that 16th ranking in 2013.
So for the most part, being at least in the top 20 seems to be the key for getting to the E8 (just one outlier in the last 6 years), and being at least in the top 16 is necessary for getting to the FF. That's pretty high up, but it's still a ways back from any view view that you have to be top 5 or even top 8 to be alive and kicking when the final three games of April roll around.