NFL teams prepare big boards in order to make quicker decisions on draft day. Most, if not all, general managers admit to referring to their pre-determined draft rankings while on the clock.
Oftentimes, you hear the phrase best player available, also known as BPA, when deciding who to select at any given spot. Even though it sounds simple, it's a subjective term. Seattle Seahawks general manager John Schneider's big board, for example, will differ from the other 31 executives' rankings.
Roster needs also factor into constructing a solid big board. Does the team already have its franchise quarterback in place?