It's a problem when they have no good options and our GM, in an attempt to save his job, puts our top prospects in there. I'm pretty sure they've already quoted someone saying Cashner is in the running for a rotation spot next year. The other part of the point is that you can't plan on awesome middle relievers, they're the most unpredictable performers in baseball. I guess you could have 3 awesome relievers to help, but that gets expensive. As it stands, the Cubs have 2 awesome relievers, plus a lot of farmhands that only need 1 or 2(if you don't trust Russell) to be okay. Plus Guzman potentially coming back. You don't need to pay a lot to get serviceable guys, teams like the Padres and Cardinals do it all the time. And while relievers are unpredictable, the one stat that's a pretty good predictor of whether someone will be a bad reliever is walks. And the Cubs young pitchers, basically without exception, excel at walking people.