Whether it's in the first round or the sixth round, finding value above expectation in the NFL draft can significantly alter the landscape of a franchise. It is easier to do that with a wealth of draft capital, of course, but how much a team can get from its draft picks relative to where they were taken is important.
If Player X and Player Y have similar seasons, the production from Player Y, taken in the sixth round, is much more valuable than the production a team gets from Player X if he's a first-rounder.