Couldn't it be that the admissions standards for Pritzker are such that the students are qualified both academically and in other ways. Even if the board scores aren't high, the people who were admitted to Pritzker likely have other achievements that are valuable to residency programs. Perhaps research or lengthy extracurricular involvement requiring a large degree of responsibility, motivation, resilience. I'm not saying that the school has absolutely no impact, but I would argue that the role of institution is less important than the kinds of individuals admitted (ie, such students would likely be successful coming out of any med school).
I'm a just-matched fourth year at Pritzker. For those of you who are interested in why Pritzker's match list looks so good given their average STEP 1 scores, here are my thoughts:
1. The AdCom is more meticulous in who they select for admission than most medical schools. They get waaay beyond MCAT/GPA scores. The interview day at Pritzker is long and for good reason. This gives both applicant and Pritzker a better chance to find out what each other is all about. The result is an amazing collection of MS I students each fall. Four years later, the same amazing collection of MS IV students apply for residency. In short, my classmates are awesome, it comes as no surprise to me that they matched so well.
2. Pritzker applicants to competitive specialties get the scores they need, even if the overall class average is not amazing. Those going into plastics, derm, ENT, ortho, etc. get the scores they need to get interviews in those specialties.
3. Pritzker does not 'teach to the boards'. Imagine you're a program director and you have two otherwise identical applicants. Both have, let's suppose, a STEP 1 of 230, but one of them attended a school which 'teaches to the boards' and the other does not. The applicant who got a 230 despite not being spoon-fed board-style questions will look more attractive.
4. It's not the reputation of the school, it's the reputation of Pritzker's graduates. Historically, Pritzker graduates have been highly successful and well-liked at their residency programs and program directors want more of the same. One program director during interviews asked me if I was AOA. After I told him I was not, he replied, "That's okay, some of our best residents in the past have been non-AOA from the University of Chicago." It's not the reputation of the school, it's the reputation of the school's graduates.
5. Lots of students take an extra year to do research or get a second degree (MBA, MPH). Having that on a residency application really sets those applicants apart. I suspect there are more of these applicants coming out of Pritzker than other schools, but I could be wrong.
6. There are tons of research opportunities here and it gets pushed rather heavily. You don't have to do research, but if you do, like #5, research can set you apart from other applicants.
Just my thoughts...