What was "The Incident" at work that caused an exodus in the work force?

They drastically altered the shift patterns from a relatively simple 2 day, 2 night, 4 off to a pretty complicated 5 on 3 off with 7 start times that you would cycle through each week. (5 straight 2100-0700 shifts suuuucked.) They also made us bid for team assignments. The real wtf moment was when they didn’t bother posting enough vacancies for everyone to bid on because of the anticipated attrition.