It is not hard to imagine a scenario where all 5 guys in the rotation have an ERA under 4 - Thornburg being the wild card. I could see the starting rotation having an average ERA in the mid to upper 3's which would be enough to top half of the NL and if things break right - healthy Yo, Peralta takes the next step, Thornburg is for real, Lohse stays like he was this year, and Estrada stays close to his last 3 years - this rotation could in the 3.5 area which would be right around the Pirates this year. Now everything could blow up and Yo could be Yo from the start of the year, Peralta regresses, Thornburg pulls a Fiers, Lohse ages quickly, and Estrada falls apart, but I feel pretty good it isnt likely. Outside of Lohse these are not soft tossers that seem likely to regress.