Bronco's classes ranged from 64 to 71 in independence. Sitake's first class was ranked higher than all of Bronco's independence classes. The second class in 2017 was right within the normal range.
As for 2018 and 2019, two seasons of 78 and and 81 aren't a dramatic statistical drop off, especially when you factor in class sizes and transfers. It also would have almost no impact on the 2019 season, since most are headed into the mission field.