It's never a crap shoot. That's just a simplification. Sometimes it's a useful one, but around here it's just turned into yet another excuse.
It's a process involving large amounts of time and money spent on compiling information about as many different players as possible (up to a point), and on targeting players that seem to be potentially good picks for the organizations. Teams that do it well will generally improve. Team that don't will generally decline. The Patriots recent struggles in the process, as most clearly demonstrated by the 3rd round failures since 2005, are a large part of why the team's been unable to successfully rebuild the defense.