I'm biased but I think that Peer Assessment score is over-rated when it comes to ranking schools like Notre Dame and Georgetown. Catholic schools aren't exactly loved by most other institutions. It's the same thing when it comes to Medical School and Law School acceptances...even though the pre-med and pre-law graduates from ND score incredibly well on the MCAT and LSAT, there's a stigma against Notre Dame. It's religiously conservative beliefs preclude the student populace, as a whole, from perhaps getting into the best schools.
If anyone has any other thoughts about the PA scoring then please let me know...I could be just looking for excuses for Notre Dame not being in the top 15