The fact is-American has set the industry standard with regard to career progression.
Is everything perfect at their wholly-owned regionals? Heck no. But with regards to career progression, they are turning their regionals into what they should have always been; a stepping stone to a major. The flow times will eventually come down and that will be the place to be. Folks will vote with their feet.
I totally get DL wanting to have higher standards. After all, last year American did crash a whole lot of planes-with every single accident being attributed to pilots who had flowed up from their regionals.