I think relief pitchers, as opposed to closers who usually only pitch the ninth with the lead, are pretty unpredictable. Sipp, who everyone seems to want, had ERA+ of 89, 81, 115, 203 the last four years. In those four years he maxed out at 1.7 WAR (1.0 fWAR) and had negative WAR seasons. I do agree there are some relief pitchers with very good track records - O'Day was the guy I wanted but not on a four year deal. Ryan Madson didn't pitch in the majors since 2011 and had a great year this year and turned it into a three year deal. Good for him.