Good points.
On D, my thought is why can't the GM simply draft good players regardless of scheme? Url, Briggs, Tillman and Pep can play in any scheme...we need guys like that. Granted, the tackles and safeties need special attention, and if a switch to 3-4 were to happen, there'd be some more adjustments...but to me, you get pass rushing ends or LB's and a coverage corner or big safety that can cover the likes of megatron... I know I'm over-simplifying, but there is some sense just to bring in pure talent.