I'm a senior faculty member at Boston Children's and I would say board scores are the least important aspect of the application for us because they don't correlate well with clinical ability or long term success. Our interns average about 255 but range from 201 to 288. Clerkship grades are very important. Most of our interns are in the top 10-15% of their class, particularly in the third year, but again there are significant variations. We interview and occasionally match people who are in the bottom half of their classes if they are amazing in other ways. We are very interested in personality, especially sense of humor, and in dimensions beyond grades: leadership, advocacy locally or internationally, research, or accomplishments in things like music, art, dance, athletics, creative writing and the like. We are also interested in applicants who have a passion and whose extracurricular activities correlate with that interest. In other words, applicants who want to do research should have a record of research, those who want to be advocates should have a record of advocacy, and so on. We certainly consider accomplishments prior to med school but we usually also expect extracurricular accomplishments during med school. But we recognize that some schools offer more time for such things and put more emphasis on them than other schools. Finally, letters are very important but particularly letters from experienced writers who know you well and write for many students (PDs, clerkship directors, senior clinical faculty, etc). And, of course, performance on an elective rotation in our program is extremely important if you do such a rotation.
Overall, I agree with the writers above who say that there is tremendous variation in the applicants we interview and match. It's the overall package rather than any one criterion that counts. We're looking for people who will have successful careers and be great colleagues, who will "fit" well in our program. I suspect that's true of everyone. So, if you're interested in a program I would just apply. Fortunately, there are a lot of good training programs in pediatrics. For most students it's not critical to be in any specific program, at least not for academic reasons. Hope that's helpful.
