Former NC State pitcher Carlos Rodon fought for a spot on the White Sox this spring, and he pitched well. He finished with strong outings against the Royals and Dodgers, concluding the preseason with a 3.06 ERA. He struck out 21 and walked five in 17-2/3 innings this spring. But he isn't heading north with the big club, and there are a couple of factors at play with that decision.
The first of those is service time, which you could look at from either a cynical or pragmatic perspective. If Rodon spends a couple of weeks in the minors, the White Sox earn an extra year of club control, which is to say that they delay Rodon's potential entry into the free agency pool by a year. While Rodon is under club control he will be much, much cheaper than he will be as a free agent, especially considering that he's a Scott Boras client.
The White Sox don't have to make Rodon serve that time in the minors now, though--they could easily work in the requisite couple of weeks during the All-Star break, or any other point in this season. It doesn't have to drive the decision they're making right now.
But Chicago doesn't need Rodon in the rotation (or the bullpen) straightaway, and the Sox really want him to develop his changeup into a pitch he can rely on. If he can trust his change, he won't have to lean on his slider as often. That slider is devastating to opposing hitters but also a threat to his health, which is the sort of thing everybody in MLB takes seriously these days. Considering Rodon's heavy workload at NC State, it's hard to blame the White Sox for being concerned.
"Yes he can pitch out of the bullpen right now but we'd be doing him a disservice if we didn't allow him to develop his changeup which he can use instead of overusing his slider, which often results in elbow issues,'' [White Sox executive VP Ken Williams] said Monday. "He only has to look at Chris Sale to know how serious we take that. Chris had to argue his way back into the rotation and promise me he was going to develop and use that changeup. That slider was going to lead to elbow problems. Once we get comfortable that he can come with three pitches, use his fastball location better and his changeup off his breaking ball then whatever role we need him in at the time is the one we'll call him up for.''
During his last start of the spring, Rodon threw 90 pitches against the Dodgers, and only 10 of them were sliders. He was still effective, though it cost him strikeouts, and he earned the win while allowing only one run (a home run off of a changeup).
That's Rodon's situation in a nutshell. He's talented enough to be effective without throwing a bunch of sliders, but his change is a bit of grab bag that he needs to refine in order to become a great starter at the MLB level. The White Sox are choosing to give him the practice time now, but he isn't going to be in Charlotte for long. Go out and see him if you have the opportunity.