Of all players drafted on a roto/fantasy baseball team, the closer spot has more volatility than a day of trading at the NYSE...well....not in the past month or so. History has shown that he who starts the season as closer has a very good chance at losing that spot by the end of the season.
Here is what happened in 2008, along with predictions for 2009:
As you can see, more than half the Opening day closers lost their job for one reason or another. How many of the predicted Opening day 2009 closer are you comfortable drafting? Lidge and Valverde have to be the top two NL closers, with Wilson a close 3rd, but after them, injury risks and inconsistent performance reigns supreme. Thus the importance of drafting the setup guys on the cheap.