In my humble opinion, Delta recognizes that Pinnacles costs are the highest in the industry. Not just the pilot cost, but all the other f'ed up costs that jack the TOTAL cost up. It is an extremely inefficient airline that can't find the elephants in its own circus tent. Barnum and Bailey would be disappointed.
Pinnacle is done. You can't just flip a switch to an airline with 2,300 pilots. It takes time to phase out the operation.
If they came out and said thy are going to wind it all the way down, then everyone would start walking off the job and the customers would be so irritated, they would vow to never again fly on Delta.
Pinnacle is a pig with AIDS and needs to be coaxed into the slaughter house slowly and carefully as to not disrupt the rest of the farm.