Why doesn't he get credit for those drafts?
Because Jerry had no input in personnel at the time. None. Zero.
I mean, if you're even only mildly retarded you can still figure out that you can't build a dynasty and then suddenly preside over the worst collection of draft classes for an entire decade.
He doesn't get the credit because he doesn't deserve any. I don't even give him credit for Larry Allen. He was working off of Jimmy's scouts and their notes that spring.
There simply isn't a GM in this league who is worse at evaluating talent. Probably because most of the GMs are real and legitimate. They have a background in it and have done well enough to advance to that position, while Jerry Jones simply paid his way in.