Like everyone else said-- it's the methodology. Research schools are ranked on a different basis from primary care schools. I'm not sure if the same criteria were used this year because I didn't take the time to read the link Spiced provided, but they used to be:
40% based on reputation by two surveys (medical school deans and senior faculty= 25%, rated on a scale of 1 to 5; residency directors= 15%, rate their top 25 choices).
30% primary care rate-- percentage of students entering primary care
15% ratio of fulltime science and cinical per student
15% student selectivity-- includes MCAT score (65%) average GPA (35%) and proportion of applicants/accepted (5%).
Then, the scores are standardized, weighted, totaled and rescaled. Most osteopathic schools won't have a chance based simply on the methodology.