This is an issue i remember thinking about as an M1/2. I matched into neurosurg yesterday and FWIW, I think personality and achievements besides just grades and step I scores mean something:
Stats:
I went to a public, east coast med school (ranked somewhere in the top 50 USNews research rankings), had a 220 something Step I, didn't make Step II available to interviewers, and was ranked at the 33rd percentile in my class (got straight Bs first two years and As and B+s my 3rd year). I did have some publications, good letters from well knowns, a boatload of well known awards from the college era, and was well liked on away sub-Is.
Interviews:
all over the place from places like MGH to UIC-Peoria to UCSF to Mayo. Only region that I didn't get a single bite from was the South-- although to be fair, I didn't apply to southern programs.
Match Results:
matched at top 5 program per my home chairman (will find out where exactly on Thurs). and, no, i didn't rank podunk university 1-5.
Lesson:
Grades and Step I are important. Med school name is not nearly as important. Most important is the whole package. And, in case you might be wondering, I'm male and not an URM.
I think the previous poster's point is correct, but it mostly applies to larger residency programs like IM or Gen Surg that take prob 20 people per year. When you're looking at a specialty that, on average, has only 2 spots per program and there are only 98 programs, PDs will look at the person much more closely. One bad apple can easily poison the dynamics of a team and disrupt things. In a competitive specialty like neurosurg, all candidates do 2-3 neurosurg rotations outside of their home institution, and these can be done anywhere (so you can get the same letters that the kid from Harvard is getting.)