If you are drafting based on your scheme over BPA, then you are doomed in the modern NFL. At this level, the players make the plays. With how much talent the Ravens and Eagles have, I don't think that argument is true. I think their coaching staff and their scheme is more adaptable than Buffalo's. The Ravens have had an excellent defense essentially their entire existence thanks to their talent evaluators and their GM, which tells me they do not draft based on scheme, at least not in the first 3 rounds. They are after the best athletes with production at the highest levels of college football.
You draft for scheme when you're in the 3rd day of the draft and you're looking at limited athletes or guys from small schools that will need to be a "fit" so to speak to be successful at the NFL level.
Is it under valuing speed or is it under valuing physicality in the name of chasing speed? I think that's where they end up with players like Bernard. A little faster than a typical MLB because they want "speed" and "coverage ability" and end up with a guy that can't shed a block of fill a gap.
I do agree that our positional value is completely out of whack. The first two rounds should be producing absolute play makers for your team. And he's whiffed big time in that regard.