There is a lot of variance, but it's not impossible to make reasonable projections. I think it's reasonable to suggest they're unlikely to be anywhere near as strong as last year. For one thing, they were a legendary bullpen last year, so by definition it's just really hard to live up to that standard. They changed the way average people think of bullpen usage. How do you lose Woodruff, Burnes, Soria, and perhaps (for all intensive porpoises) JJ and not get a lot worse in the pen? A couple of Peralta's best games were technically relief appearances as well. And while they still have Knebel and Hader, I think the most reasonable projections should have the pen regressing a lot, despite the standard disclaimer that bullpen performance is pretty volatile. On the plus side, some of the best arms are going to the rotation. Manage innings and make a successful transition from Anderson/Davies to Peralta/Nelson a few months in, and the rotation could more than make up the difference by the end of the year. Your hypothesis is certainly possible. I guess I just prefer to view the state of the pen in a little brighter terms. I think its entirely possible that Knebel is more stable this year. I don't think they are really going to miss Soria's small-sample 22-inning, 4.09 ERA stint, although he was better than that in the playoffs. But in theory you are eliminating roughly 70 innings of cringe-worthy Oliver Drake, Boone Logan, Aaron Wilkerson and Matt Albers appearances (although Albers is likely to make the team again, I doubt they give a long leash if he's horrible). In the end, the fate of the pen rests on guys like Taylor Williams and Jacob Barnes being able to capitalize on the good points they had last year. Are the decent ERAs they put up last year mirages? We'll see.