The union gave up any leverage they had when they agreed to back the skywest deal and *hope* for better later.
The company doesn't have to do anything. They can come back and say "lets meet. Ok, no soup for you. Deal is done. "
Not having the 600 this year IS leverage. The company will increase pay because it has to, not because of the union. They are doing the best they can.
If I had seen these emails when I was deciding where to go, it would have been a helpful insight.