The thing about Kiper and any of these overall draft boards is they are devoid of context.
A guy might be the "Best DE available" but he plays a 3-4 and all the teams with needs play 4-3. A guy might be the "best QB available" while never having run a pro-style offense. A guy might be the "best WR available" (Da'Rick Rogers, anyone?) but have major character or injury red flags. We've seen plenty of "talented" players go to seed in the wrong scheme or wrong coaching situation, and plenty of overachievers in places like NE or Baltimore.
So, the problem is not Kiper or McShay exactly, though both are kind of idiots at most things besides drawing attention (and therefore ratings). The problem really lies with the whole premise of draft ratings and draft prognostication being equivalent sciences, if they're sciences at all.