I think grapefruits has a point here, however indelicately he/she may have put it.
Why else would law schools so prominently display all those fun statements on their websites like "our incoming class represents X number of countries, X number of states, alllllllllllll of the following foreign languages, etc"? There is more to creating an impressive incoming class than just numbers. They do want to put together a diverse class w/ the highest numbers, no doubt, but if you bust their medians and don't possess any other soft characteristics that they are specifically looking for, I can easily see an adcomm WLing a numerically competitive applicant. As for taking that personally... I would recommend against that. Maybe an applicant has all kinds of interesting soft factors, but the school has already admitted other kids w/ similar softs earlier in the cycle and that specific later applicant just doesn't offer anything unique in that cycle.
As far as data, I think we're seeing at least some anecdotal evidence that adcomms WL/deny applicants with above median numbers right here on TLS.
ETA: looking back at it, I realize that ph was probably saying that he/she would like to see some data on the extent to which this happens, not that he/she was doubting that it actually happens. ...my bad.