How important is drafting well to sustained success in the NFL?

With quarterback seeming to be off the agenda in the first round of the upcoming draft (or is it?), discussions on Hogs Haven have been focusing on what elite play makers at other positions Washington might consider targeting with the 11^th overall pick. One of these discussions got me thinking about the concept of position value, specifically whether it might be counterproductive to rule out certain positions at #11. This prompted a broader exploration of where elite players are taken in the draft, and whether some teams are better at finding them than others.