Sure, as I said upstream, they probably get the vast majority of decisions right, but there seem to be an increasing amount of randomness. My kid is in the top 10 rank at school, and their counsellor said many kids in their spots in previous years didn’t get their top 5 UC choices. The throw-away answer is that those kids had issues with their PIQs/ECs but I often wonder if given the sheer volume of applications UCs just make some errors and given each app is read independent for each school some kids just get really unlucky.
I think even Davis now gets 100K applications and they mail out decisions in about 100 days so that’s 1000 apps a day reviewed during the holiday season!
I’m super glad we have all these great universities in state.