The White Sox have a rotation headed up by two development miracle babies. They brought in Chris Sale, who many saw as a reliever when he was drafted, and Jose Quintana, who no one saw much of at all, and developed the into and unimpeachable No. 1 & No. 2 pairing.
The Sox organization knows more about pitcher development than I, and all of their audience does. The professional baseball organization knows a lot about baseball. This is great talking point if you would like to sound sage and above the fray while simultaneously cutting yourself out at the knees. The mayor knows more about running a city than all of us, the police know more about policing than all of us, restaurant servers know more about food preparation, but no one is nuts enough to just sit back and rely on their expertise.
The fourth estate is doomed to be permanently less informed than the people they are tasked with holding accountable, on what they are holding them accountable about. They have to try to pick it up piecemeal and through context clues, and hope they get just close enough to the truth that they force out a real response from the parties they cover.
So, using context, it's hard to understand what the motivation would be for the White Sox to use Carlos Rodon out of the bullpen next season, as they were reported to be considering back, oh, two weeks ago; back when there was White Sox news worth commenting on.
The reason for putting Rodon in the bullpen during the 2014 season is easy enough to understand: it was a means of getting him MLB experience when he couldn't be expected to be readied or completely stretched out for the rigors of a starting against MLB competition. It was a way of testing out his ability to retire MLB hitters before ramping up expectations for his big league viability next season.
The reason for putting Sale in the bullpen, while not without controversy, was also easy enough to see. He was capable of providing immediate assistance to a unit that could use the help, and Edwin Jackson filled the only significant injury gap in the rotation, and he was again, not stretched out or prepared for MLB starts anyway.
Rodon in the 2015 bullpen, well...
Sure, the Sox might not have a decent left-handed reliever in the organization at this point, but filling out their rotation is still a larger need, and it's one the Sox can wait for. Rodon could easily provide more value and innings as a starter rather than a reliever., even if he needs to work in the minors through June before starting.
If it's not a developmental issue, it's not much of a health measure. The life of back-to-back days of max-effort work, or back-to-back-to-back days of work and rushed warm-ups is not especially more kind than a regular throwing schedule for a 200-inning workload.
It's an extremely safe assumption that there is a method to any White Sox pitching madness. If Rodon's changeup and command are not ready for success as a starter, working in relief could allow him to contribute to the major league club while working one-on-one with Don Cooper, while fulfilling any possible promises for quick promotion.
But for the most part, I find the reasons for any deviation from developing Rodon as a frontline starter as uncompelling and unnecessary. Start him.