Confirmation bias.
Go look at Cal's teams in the tournament from the beginning til now. Go look at the box score of their final game.
Everyone is nervous in the Final Four. That's a given. And UK is at the F4 constantly. But our upperclassmen consistently see the same or usually a bigger hit from their normal performance than did our freshmen.
Go look at who came through for us in the 2010 E8, 2011 final four, the 2012 championship, the 2014 championship game, the 2015 F4 game, hell even the Robert Morris NIT game.
The best 2-4 players were ALWAYS freshmen in those games - and it's not like UK hasn't had unbelievable upperclassmen in that time. Junior Patterson, Senior Darius Miller, Soph Terrence Jones and Doron Lamb, Junior WCS, etc.
Hyper Elite freshmen who are used to playing the very best in AAU tourneys don't choke any more than upperclassmen. That narrative just doesn't jive with the numbers. At least not at UK.