They'll watch tape and watch combine workouts and watch pro days. They'll discuss and debate and come up with a draft board.
And they'll still miss.
No matter how much work NFL teams put into the draft, someone is going to get overlooked.
NFL.com has a handy little article demonstrating this fact once again. It points out how the top five players from last season in several categories include lots of players selected in the fourth round or later or not even drafted at all (for example, the 2011 leader in tackles -- the Redskins' London Fletcher).
So, no matter what Mike Mayock, Mel Kiper and Todd McShay say, there's an awful lot of luck involved.