In thier defense you cant predict how the draft goes accurately. What they do is say who are the top x amount of prospects then based on teams who they should take. Their jobs arent based on how accurate they made out with thier mocks. You can go back and see how they viewed certain prospects and what happened to them.
They do have the best jobs and they are deep with who they know. I mean Mel Kiper may look like the kid from the Munsters (grownup version). And he may flop on picks he feels is this high, should go here, who made mistakes. But I give him props when its rd 7 and this mofo has information on a kid from a school you never heard of.
Thats dedication and preparation my friends.