I disagree to an extent, I liken it towards the Suh-McCoy argument except Fairley wasn't as consistently effective as Suh. Fairley was a bigger impact stat wise, but I think they are on the tier talent wise. There's no bias either, both of the players are 2 of my favorites, Fairley more so than Dareus...
I'd agree about the similarities to Suh/McCoy, mainly because it's one of those deals where two guys may be right next to each other in the positional (or overall even) rankings, but there's still a definitive line between them, at least for me. I don't dislike Dareus, I think he's one heck of a player and I'd put him even higher up my list after what he did at the combine. I'm actually impressed that he put that much into preparing for workouts. It really just comes down to that fact that I strongly feel that Fairley is the best player in the draft. If the question was how could someone take Fairley over Patty Peterson, I'd say the same, even though I think PP is phenomenal player and the 2nd best in the class.
