Though many fantasy football leagues have switched to an IDP (individual defensive player), many still use team defenses for fantasy defenses -- including my league.
Despite the fact that the Dallas Cowboys have revamped their secondary by adding Brandon Carr and drafting Maurice Claiborne, Yahoo! Sports doesn't think much of Dallas' defense for fantasy purposes. The Cowboys are ranked as the eighth-worst fantasy defense headed into 2012, meaning, they should go undrafted in just about every fantasy draft.
The usual suspects are atop Yahoo!'s list, with the San Francisco 49ers, Pittsburgh Steelers, Baltimore Ravens and Chicago Bears occupying the top four spots. There's seldom any good reason to draft a team defense early, so you're better off letting somebody else in your draft reach for any of those defenses.
I'm not sure I agree with Yahoo!'s assessment in this case. For the most part, team defenses can be a crap shoot headed into the year, at least for fantasy purposes. Rob Ryan's defensive scheme relies heavily on the secondary doing its job, so that Ryan can get creative with his blitz packages. If Carr and Claiborne play to their abilities, then Dallas' defense could force a lot of turnovers and register a lot of sacks.
Dallas' safeties are cause for concern, though, as they are easily the weak link in the secondary, and on Dallas' defensive unit as a whole.
If you're stuck at the end of the draft and you're looking for a defense to gamble on, Dallas isn't a bad choice, and neither is another much maligned defense as of late -- the New England Patriots. New England used a pair of first round picks and spent nearly the whole draft revamping the defense.
You could do a lot worse for a fantasy defense than the Cowboys or Pats toward the very end of your draft. And even if they don't work out, you can always just stream defenses weekly and just pick out the best matchup on the free agent wire.