I'm not a Delta pilot but it seems either Delta provided a healthier work enviroment in the past and the last decade of changes is causing the workers to wear down. The FAA has come out with new guidance on self assessment for aircrew concerning fatigue and readiness to operate aircraft and aircrew are required by regulation to follow them.

The new increased sick usage will soon be the new normal sick leave usage. It appears that not calling in sick in the past means that a sickness in the future will be considered abuse.