I've been intentionally staying out of this thread, but I can't anymore...
Numbers don't tell the story-- bigger schools will tend to have more accepted because more apply. On the other hand, percentages aren't terribly useful either for all of the reasons listed earlier.
As a 16 year old first year, my premed advisor told me that I shouldn't consider medicine because I got a B in first semester physics. She basically told me the committee wouldn't recommend me. However, the old bad retired and the new committee recommended me without hesitation. In the last 9 years, I've gone to grad school, done research, and published a dozen articles. I got in to several top tier med schools. So, the school doesn't always know everything, but they can make it difficult for someone to apply if they desire.
In the end, I think top tier schools (small liberal arts colleges and universities) have a solid record of getting students into top schools. Is that really a surprise? Med schools get quality students year in, year out from the top schools. Fair? Maybe not, but true. And students get into med schools without people to hold their hands throughout the process like I had. And they have truly achieved a feat. I just went to my advisor and said, "what do I do?" and they told me. That's why there's a 90% acceptance rate. They make sure you have everything done in the manner in which it needs to be...I guess that's what my parents paid $120,000 for, huh?