The premise of this post is simple, so I'll keep the intro short and sweet. The Cubs have finally come to their senses and decided to move Zambrano back to the rotation. Now, obviously, this begs the question: who's the odd man out in the rotation? Rundown of the pros and cons of the candidates below
Note: pro is a reason to move him to the pen, and cons are reasons not to.
Pros: Power arm that's ideal for a late-inning guy. Right-handed, which helps with balance. Has been ineffective in rotation this year
Cons: Has been ineffective in bullpen this year. Has been better over the course of his career then any other Cubs' starter. Has huge contract - this does matter and here's why. Before you naysayers start with your sunk-cost argument, Zambrano is signed long-term, while guys like Randy Wells and Gorzelanny will be arbitration eligible. I'm going to define value right here as production/salary (obviously production isn't completely quantifiable, but this is a theoretical discussion). Zambrano's salary over the next 3 years is fixed, meaning his value will be solely dependent on his production. So to get the most value of him, you put him in the rotation where he can eat the most innings. For Wells and Gorzelanny, their salary is dependent on their production because of how arbitration works. Put them in the bullpen and they'll be less productive, but relievers get less $ in arbitration, so having one of them in the pen doesn't hurt us as much as having Z in the pen does, assuming equal production. Another way of looking at it is that the Cubs operate on a fixed budget, therefore winning as many games as possible involves getting as much value as possible out of that budget, which is why you need to get as much value out of Zambrano as possible, because like it or not, we're tethered to him.
Pros: May not be 100% yet (his velocity is down this year, according to Fangraphs, although that may just be age-related decline), so he may benefit by working out of the pen for a couple weeks until he gets his arm strength.
Cons: Not really suited for a pen role, as his strength as a pitcher lies in his balanced repertoire, which isn't as much of a factor when you only face a guy once. He's also very good. Also a lefty.
Pros: Has bullpen experience, I guess.
Cons: Has been the Cubs most consistent and reliable starter over the past couple years. Moving him to the bullpen would be beyond stupid. Also has a big contract (see Z's cons)
Pros: Is a righty, for what that's worth. Doesn't have as much of a history of success as Z, Lilly or Demp. Small contract.
Cons: Has been very good as a starter. He's young so he probably figures to be a rotation fixture for years to come.
Pros: Has a spotty track record overall for his career. Out of the 6 pitchers here, has the worst career ERA. Small contract.
Cons: Has also been very good as a starter this year, and his peripheral stats indicate that he's going to continue his success. His BABIP against is .353, which shows that if anything, he's gotten unlucky this year and should have better results. His FIP is a stellar 2.72, due to the fact that he's striking guys out at a much higher rate compared to the rest of his career. I think that trend continues because his strikeout rate last year was pretty high too. Also a lefty.
Pros: Out of the 6 pitchers listed here, he's had the 2nd-worst career ERA, behind Gorzelanny. Has been absolutely awful recently, except for this year. Unlike with Gorzelanny, Silva's peripheral stats do not indicate that he will maintain his performance. His BABIP against is only .283, which implies that his success this year has been nothing more than sheer luck. The ground balls and line drives haven't found as many holes as they would on average, and the bloop pop-ups haven't fallen for hits as much as they would on average. This trend is not likely to continue, and Silva will regress to his average, which is pretty bad.
Cons: Has been good this year, I suppose.
Finally, I've attached a poll. At this point, it should be obvious which player I'm voting for, and it should be obvious for you too.