Value is a moving target regarding the NFL draft.
All 32 NFL teams don't work off the same board to determine who the best value is for them. Typically, each organization's rankings are pared down to much smaller than the size of the overall class and the public offerings from outside sources.
Hall of Fame general manager Bill Polian used to tell his scouts, "When the talent line meets the need line, you usually have a good chance of hitting on the player."
The reality is that teams still regularly miss on picks and pass on other talents that go on to be successful elsewhere.