How NFL teams ignore basic economics and draft players irrationally - Vox:
The problem, though, is that there are no guaranteed superstars — and Thaler and Massey have found that, given a long enough timeframe, no teams are any better at accurately evaluating prospects than others. Sure, a GM might hit a hot streak over the course of a few drafts, but long-term, they estimate that 95 to 100 percent of the difference in teams' odds of striking gold with any one pick is driven by chance.
So the key isn't drafting better — it's just drafting more.