The thing is the cover 2/Tampa 2 - whatever you want to call it has been effective since the Steelers in the 70's. I think a coach has a shelf life.
So do players. Hell of a lot easier to run that with Brooks, Barber, Lynch, Rice and Sapp. Kiffin had those 5 and the Cowboys do not have 1 as good as any of those players.
Scheme is the recipe and the talent the ingredients. Until the Cowboys get better on the latter, I don;t care what dish gets ordered. Parcells wanted to run the 3/4 but missed one little detail, the players to execute it. When Landry introduced his Flex, he struggled initially with getting players to understand it but he began to pick specific players for it and even he missed, both Harris and Watters were picked to play CB and became known as "burnt" and "toast" but a great D mind finds a better place for great players.
I don't know why we got down on Marinelli, the guy was a DLC, not a DC. I don't know why he was given any play as a talent picker. Now, Hill may prove me wrong but he's was picked solely on Marinelli's thumbs up. I understand he wanted Charleton as well.
One problem is that too many think McClay is the end all. The guy has been good with OL....in the 1st round. The jury is still out on OL picked after that. OL is the safest pick in the 1st round of the draft.
Byron Jones was picked because he was that year's Combine Freak Athlete and they needed a CB and looks like they'll be needing at least one more out of this draft.