Definition: Drafting somebody at least one round earlier than you needed to, and thus missing out on a better player plus the guy you drafted anyway. Regardless of production, nothing warrants picking the player early. 

Origin: The day of my fantasy draft I was talking up Jason Campbell, and I jokingly said if I got the first overall pick in the draft, I would draft him. By saying that joke, I realized that there is no way to warrant picking Jason Campbell first, even if he has more fantasy points than the rest of the league combined. The reason is because even if he has a superb season, his value is many rounds lower and you can still get him later in the draft, in addition to a great number one pick. Now wouldn't it make sense to have the great number one plus the 9th round overachiever. I think so.

In a sentence: Guy 1: "I took Brett Favre over Peyton Manning because I think he will have a great year." 

Guy 2: "Classic case of The Jason Campbell Theory"