Andy Behrens of Yahoo! discusses the dilemma of when to take a fantasy defense, focusing on the Minnesota Viking defense in particular.
I actually think the Viking Defense will be a fantasy disappointment. They will improve as a defense overall, and for fantasy purposes, they should have more sacks, fewer points allowed per game, and a solid number of turnovers. But the Vikes had a ridiculous number of defensive touchdowns last season. I don't think it likely the Vikes will have close to eight (EIGHT!) defensive touchdowns again--that's just fantastic, and requires too many breaks to happen again.
So the Vikings will likely be clumped in with a lot of good defenses in fantasy points. And that's fine--they'll be good. But somebody (especially in drafts filled with Viking fans) is going to take the Viking Defense too early, passing on position players that could help a team, and being disappointed when a handful of fantasy defenses drafted a few rounds later outperform the Vikes. I'm actually the only fantasy owner in the six-year history of the Hazelwierd League to ever have the Viking Defense on my roster. That's going to change this year.
Then again, in a Snake Draft, you can't think that way--you have to target the players you really want, and take them when you can get them. So, Viking fans, feel good if you do draft the Viking defense. You'll still get to root for the entire squad (which you would anyway), and get fantasy points out of it too.