As I said before, there is no "bottom 5 percent" in a MBA class. I suppose it's possible to fail business school, but I've never heard of it happening. There are a number of classes where if you show up, and write a paper, you get an A. Grades are not important and have nothing to do with where you end up. If you're talking about the bottom 5% in terms of outcomes, the worst case scenario is that you have a degree that has a great deal of inherent value. MBAs from top programs carry as much value as MD/JDs from top programs, despite being two years and many times paid for by your employer. Clearly if you went to a worse program, the degree could have less value, but again, we're talking about the "best" SMP, so apples to apples.
One could say my situation is as close to a "worst case scenario" as you could get (although I did get a promotion equivalent to 4 years of work experience after finishing my 2 year degree, I only worked in business for ~4 years after it before I decided to go to med school) and it was still a fantastically useful degree. I credit a good portion of my success in the app process to the prestige of a top MBA. Furthermore, access to incredible alumni resources/networking have value in all situations, even ones that on the surface seem not at all business related. I recently ran into a technical problem in a lab I am working in in which the vendor we were working with wasn't being particularly responsive. A quick check of my address book and a call to a classmate of mine (who is a director at GE, the company in question) and the problem was resolved. Apparently their normal product development/update cycle and time to implementation of changes was in the 2-3 year range. Networking is important in most fields but I don't see the access to alumni networks/networking anywhere near as powerful for JD/MD degrees simply because you meet less people and it's not as essential. Since I'm planning to practice for some time then return to the medical device industry, the degree will probably end up being more valuable than my MD fwiw... food for thought.