Higher peak vs longevity. You could argue that KW had a tougher SOS in a P5 conference, but BYU went 5-0 against the P12 in one of those conf championship years including a win over Utah (and we don't even think of that 2021 team as being one of BYU's best teams all-time), so the SOS is up for debate. Kyle also benefits from the success Urban started, similar to how you can say LeBron benefited from MJ paving the way.