Well, there are only so many interview spots, so regardless of the number of applicants, the interviews are relatively fixed. Because of this, our average board scores per interview class varies a bit from year to year (based on the number of applicants in the pool). If you get tons of applicants, then you interview only the cream of the crop. If you don't, then there are going to be some interviewees that on a different year might not have gotten a spot.
While some people are clearly the rock-stars of an interview class, most people who get an interview are, in fact, more or less on an even playing field. We wouldn't waste time interviewing you if we wouldn't consider taking you. But I do suppose you're right, some people need to shine a little brighter on interviews than others in order to boost their stock. During the interview, we are probably trying to sell our program harder than you are trying to sell yourself. This is not dermatology -- we can't act like jerks and still expect you to rank us highly. Mostly what we are looking for is whether or not you seem to fit in with us, in terms of your comportment, goals, attitude, etc. These goals are often shockingly different from program to program, so I strongly urge you to look at the residents and see whether or not they seem like people you identify with.
While I know med students like to think of everything in terms of board scores, I strongly caution you to avoid this mentality. There are always a few bozos with a 270 on step I who think they're going to breeze into the program of their choice. It hurts them. Then there are others with a 210 who think "I'll never get in here" and act like a shrinking violet on interview day. It hurts them too. Everyone brings a different skill-set to the table, and you should be confident in yours. No good program wants only PhDs, or only people with 260+ board scores, or 5+ publications, etc. If they're interviewing you, then they probably want someone like...you! So relax, focus on whether or not YOU like the program, and don't say anything to hurt your cause. The rest will sort itself out.
