...greater than their number of wins from 1966 to 1969.

BYU's record in those years was:
1966: 8-2
1967: 6-4
1968: 2-8
1969: 6-4

Sitake's record was:
2016: 9-4
2017: 4-9
2018: 7-6
2019: 7-6

So 13 games per season for Sitake vs 10 games per season for Hudspeth. Sitake's teams played 12 more games in their 4 year period.

Sitake's win percentage for his four years was 51.9%

Hudspeth's win percentage for his four years was 55%.

The movement was simply due to the increased number of games per season offsetting the lower win percentage.