From their scouting reports, they can guess roughly the needs of that team but teams like Atlanta are so random. Who knows what they're thinking. Anything goes on draft day. They might see something during a workout that vaults a player up their draftboard. If GMs have a way of predicting draft order that fans and sportswriters dont know about, they aint talkin. It's funny to me that you can take a general consensus mock draft and rearrange several players and it's almost guarenteed that it'll come out closer to the actual draft.