Well, the main reason, though already covered, is that while the Nationals aren't terrible, they won't win as many games. Cordero is great, don't get me wrong. But 35ish saves is what I'd bank him at, and then you consider the WW guys every year, and I wouldn't buy Cordero at a high price. If Cordero fell to 6th - 7th or so, I'd consider him. Not necessarily like top 50, though he's on the border.