Joba was a frustrating player to see this year. It seemed like at times he refused to throw strikes, and couldn't give us a quality start to save his season. This came after what was a pretty good year as both a starter and releiver in 2008. He went from a 2.60 ERA with 12 starts and a number of relief appearances in 2008 to a 4.75 ERA throughout 31 starts in 2009. Does he just not have it? Should he be sent back to the bullpen where he's experienced success in the past?
Let's consider player B for a moment. Player B, posted a 2.67 ERA through 12 starts in his first season pitching in the majors. The next year he frustrated fans, by having 31 starts with a 4.52 ERA. In other words, very similar numbers to Joba. This season, player B is in the Cy Young conversation with a 2.49 ERA, and 19 wins in 34 starts. This player is Felix Hernandez.
Now I'm not saying that Joba is the next Felix Hernandez, but what I am saying is that some really good prospects had their bad seasons. It took Felix Hernandez two seasons after that rough year to settle in as a pitcher and put up the numbers he did this year. Imagine if they had traded him back then? Joba's may still be too young to give up on.