The mock drafts and draft experts are affected by the Independent Scouting services that many teams in the NFL use. The problem is that they are about as accurate beyond the first round as a monkey throwing his out feces at the stock pages.
The only "Draftnik" that was worth his weight was Joel Buschbaum. And even his scouting missed things.
You have numerous teams in the league now that don't use the Scouting Services and, therefore, have their own way of evaluating players. Particularly when it comes to the intangibles. Which they get from their own interviews with players. And I guarantee that plays a bigger role in how they view players than it does with the Scouting Services..