Does it really matter? The USNWR rankings are suspect to begin with, IMO. They rely heavily on reputation, and also on research funding. Both of these factors are irrelevant to most students because:
1. Reputation is a tricky thing. It can vary regionally, and being highly ranked makes a school more likely to be ranked high in the future. (Can you see why this is absurd?) Besides, reputation for what? Good clinical? Good basic science? Good residenct training? (which doesn't affect med student so much)
2. Research funding is equally hard to call. Unless you're MD/PhD, does it matter? I *am* MD/PhD (app), and I can tell you even then its not the end all. There can be lots of money at a school, but if there's no faculty you want to work with, it doesn't mean squat. Plus, there are factors about programs that aren't taken into account by these numbers.
I won't go so far as to say prestige doesn't matter, but it's only a small factor among many.
-Naphtali