Chemist, congrats on your son's success. It is tough being one of the youngest in a class year.
As for your comments, I'n not sure the national experience applies since it's hard to qualify for an L3 without some previous success at a tournament with national points, which puts you on TRN's radar screen.
However, your comments about geography interested me, and here's what I found. 151 beating 51 was Mountain/SoCal. 178 beating 92 was Norcal/Norcal, 327 beating 179 was TX/Norcal and 278 beating 95 was Mountain/Southwest, so at least 3 of the 4 matches were cross-geo.
Initially, I was surprised by which geos succeeded in these match-ups. However, I've suspected there is a potential bias in TRN rankings which may assume that some geos are stronger than others when it does to resolve conflicts in the data. To be fair, I have no basis, other than the numerical upsets in cross-geo play for suspecting this, and I know that folks at TRN have said they need cross-geo play for calibration, but they had to start somewhere.
In addition, knowing that in at least one case it was a younger sr. beating an older senior, that upset doesn't surprise me either. I've long thought TRN underestimated boys competing against other boys currently aged 16-17 (mostly juniors, but some young seniors). At least in our geo, this group (those who recently aged up or are in the process of doing so) is quite deep and is pushing very hard on the boys immediately ahead of them, many of whom played up early and didn't benefit from the tougher competition.
All-in-all the good news is that the competition is strong and getting stronger, at least until USTA National has their way