You've probably heard of the Joba Rules.
Concocted by the Yankees and proliferated by the media, the "Joba Rules" simply were to be very careful with Joba Chamberlain. The Yankees used their young ace-in-the-making very conservatively this season, starting him in the bullpen (and not letting him pitch on back to back days), and then slowly transitioning him into the rotation. It worked seamlessly, as Joba has been extremely successful throughout the entire season. In 78 innings between the bullpen and rotation, Joba has a 2.30 ERA and 93 strikeouts. That's impressive.
Conventional sabermetric wisdom generally dictates that no young starter - especially one as fragile as Chamberlain - should exceed his total innings from the past year by more than approximately 30 innings. Tom Verducci originated this dictum. Of course, every pitcher - indeed, every person - is different and should be treated accordingly. However, there is no denying that if any pitcher called for a conservative course of action, it's Chamberlain. Between his past health problems and his tremendous ceiling, it behooves the Yankees to be cautious with Joba; hence, the Joba Rules.
Last season, Joba pitched in 116 innings between the minor and major leagues. The Yankees likely wanted to limit his innings this season to 140-150, thus setting him up to pitch 170-180 (nearly an entire full season) in 2009. They monitored his bullpen usage closely and began his transition to the rotation at the point in the season where Joba would finish the season right around his targetted innings pitched (and perhaps even have some left over for the playoffs).
However, as you know, Joba is currently on the disabled list. He has pitched only 78 innings thus far this year, and although he is likely to pitch again this season, he may return as a reliever. Even if Joba returns as a starter, he likely won't make more than five starts over the course of the rest of the season. Even if we expected him to average seven innings per start - which is highly unlikely - Joba would toss 35 more innings this year, giving him a total of 113. Thus, it's very unlikely that Joba's innings count from this season will exceed his innings count from last season.
What does this mean for next year? Well, it would seem to mean that the Yankees will be in the exact same position, next year, as they were going in to this year. Joba is still a highly talented young pitcher with a recent history of injuries, coming off a season where he pitched in less than 120 innings. Thus, it makes sense, once again, to limit his innings total so that he doesn't pitch many more than 150, if that. There's a good chance that I am missing or overlooking something, but, on the surface, it appears that the Yankees will have no choice but to institute the Joba Rules again next season.