I scored very high and would like to think it was a factor, but honestly once you reach 155-160 per section, I doubt it makes any difference or gets looked at again--especially for Social. 150 or below would probably be somewhat of a factor, but this is not undergrad and I don't think they're looking at test scores as this person got a 157 and this person got a 165 so Person B is better. Those two would pretty much be the same, and they turn to the other more directly relevant factors like recs, experience, fit, statements, pubs/posters. Michigan is a top program and their averages were 155 & 159 last year.
I think it's far from the science (no pun intended) that undergrad admissions more closely resemble.