The problem with looking at the percentage of people into fields is that it assumes people are all going to go to the most competitive field they can get. This is a pre-allo attitude that will ultimately break once you get to med school and actually start to think about what you actually find interesting. Truth of the matter is, the top student at most schools doesn't opt for derm even though s/he could get it. I know many top folks who did IM, or surgery, rather than one of the more cushy competitive fields. Other folks make choices based on geography, family, etc. So the question is really did only 20% get ortho or did only 20% want ortho -- no real way to know this, and it can make the match list interpretation meaningless.
Additionally, you have to look at a couple of years of match lists because a school that matched a high percent of folks into a specialty last year and a lower percentage this year just may mean the folks they recruited for this particular class had different interests, not that the school had any impact.
So I still say, waste of time at this juncture.