Regarding the flow thru, DAL management is not very fond of this program.
First, the program is difficult to plan for because Compass and Mesaba can hold line pilots for 90 days, management and linecheck pilots for up to 9 months. When Delta hires, they hire to have out on the line as soon as possible.
Second, DAL does not interview these folks and thus has no say in the quality of the product. (I'm not slamming the pilots of Compass or Mesaba, no disrespect meant, just stating the reality of the program). Management has acknowledged that some of those pilots do not have a college degree and thus will end up working for DAL. They're not happy about this. However, future pilots hired by Compass and Mesaba will be required to have degrees.