In every single draft, there are booms and there are busts. JaMarcus Russell, a subpar quarterback, was drafted first overall. Tom Brady, arguably the greatest quarterback to play the beautiful game of football, was drafted 199th overall.
Scouts are constantly searching for the answers of whom to draft and whom not to draft. They browse through categories—skills, intangibles, statistics, team production, etc.—but still can mess up a high draft pick. Diamonds are found in the later rounds, however.
Brady is just one example of what great scouting can do to a team. In this year's draft, there is no shortage of late-round steals.