The NFL draft is an inexact science in a wide variety of ways. Great college players often become mediocre or bad NFL players. Players that had average contributions in college become stars at the next level. First-round picks play like undrafted free agents and undrafted free agents turn into Hall of Famers.
There is little “known” about how to draft well. The teams that draft well are often rewarded but even then it is hard to put your finger on what makes that team better at drafting than others.
In the end, success in the NFL often comes down to the best quarterback with the best weapons and the best coaching.