I preface this by saying I will be a PGY-1 at Mayo in IM this July.
All I can say is if Mayo was located in a major city, say Chicago, it would be almost impossible to get an interview. The fact is, many people are turned off by the thought of living in Rochester--which I think is an uninformed decision especially when people don't apply simply for that fact. There is a historical reason why the Mayo brother's father picked Rochester to settle down, and that is part of the allure of the institution. I worked with several Mayo residents, know many more from my school, and can say hands down they are the most polished people I have ever worked with. Their fellowship match speaks for itself.
I too am pretty sure I could have gone whereever I wanted--including some very big names on the east coast, but I picked Mayo because the learning environment is incredible, but most importantly, the people you work with are incredible. Frankly, some of the residents at other "prestigous" programs came off as arrogrant, self-centered, and pretentious. In the end, I wanted to work with like-minded people who could help me advance as a physician.