I must say, Kuo is, to me, among the most enigmatic players in baseball. Kuo now has a total of 85 IP at the major league level and 169.2 in the minors. He's spent most of his career sidelined by injury, and while the backstory is very different, he's similar to Josh Hamilton in that it's very difficult to feel at all confident in projecting his performance. Kuo obviously has talent, as he's struck out more than a batter an inning at every stop in his career outside his present cup of coffee. At the same time, he's had very high BABIP's at every level. While I've generally known a lot about most players coming up the Dodgers' system, Kuo kind of slipped through the cracks because of his injuries, and so he wasn't on my radar, even after his September call-up in 2005. It wasn't until he showed up in the Dodgers bullpen in April 2006 that I really took notice, just kind of dawned on me in 2006 that and even then, he didn't seem all that noteworthy. He wasn't even doing all that well in Vegas, and while I probably should have noted the obscene number of strikeouts he was accruing, I didn't. Then all of a sudden he was converted to starting, which sure as heck didn't make a lot of sense - why convert him to a tougher role? But suddenly, Kuo's overall numbers improved, and he was back in LA, this time as a starter.
It has now become commonplace among LA fans to assert that Kuo can only start, not relieve. One does not often hear this said of pitchers, and normally when it is said the logic is off. In this case, though, it may be more accurate. Kuo's major league numbers as a starter are 47 IP, 2.68 ERA, 41 H, 50 K, 13 uBB, 1 HR, for a 2.18 FIP of and a szERA of 3.06 as well as a .317 BABIP. As a reliever, he's got 38 IP, 6.16 ERA, 37 H, 46 K, 27uBB, 3 HR, a 3.80 FIP, a szERA of 4.10, and a .347 BABIP. Obviously, the outcomes have been considerably better for him as a starter. And since his split has been the opposite of the typical - essentially, his split would be about normal if his starting numbers had instead come in relief and his relief numbers came as a starter - it's certainly fair to believe there's a good chance he's better as a starter.
However, I'd argue that Kuo probably is not somebody who's much better as a starter than as a reliever - his split would probably be smaller than typical, but I suspect that over a suitable sample he'd actually do better out of the bullpen. Others will surely protest that he's just better suited for the rotation, biorhythmically or in some such way. I think, however, that that's a post hoc quasi-scouting observation. I think it's more likely that Quo improved when he converted to starting because he was so inexperienced. Kuo obviously has quite a bit of talent, but was inexperienced enough that he had a tough time above AA and was walking more batters and perhaps setting up batters to hit the ball better. But maybe Kuo simply became a better pitcher when he started because it was the first time he was logging a considerable amount of innings, and he was learning much more than he had been as a reliever. His starting stint was all at the end of the season, and for someone with such a tiny amount of minor league work, we would expect the in-season experience to matter quite a bit. Or, rather, I think we would expect that. While some will point out that Kuo has pitched better as a starter this season than in relief, that kind of ignores that his relief stints were when he was just coming back from a shoulder injury and that the sample size is close to meaningless.
While we might possibly have sufficient data to conclude that Kuo is better as a starter, that's not the data that most are using to paint Kuo as starter-only material. That is, the very granular data might indicate that he doesn't gain the typical relief advantage and in addition gains other advantages by having a better approach while starting. Tentatively, I think that that's just over-reacting to a little bit of data. In reality, I think Kuo is probably a good starter who would be a good reliever also, and hence, like essentially any pitcher, Kuo probably in reality would put up better numbers in a full-time role than in the rotation.
That's not to say Kuo should be in the bullpen. I think it's probably best for all involved parties to have him in the LA rotation. He seems as if he's going to be (and is already) a very good pitcher, and he should be better than Tomko and Hendrickson. However, I caution against the Dodgers (and their fans) deciding that Kuo is only good as a starter. What if Kuo, pitching in the rotation, goes through a rough patch, and starts to look like he's more of a 4.00 ERA pitcher for the time being? And let's further assert that Billingsley continues to pitch brilliantly in relief. I fear that the Dodgers might stick with Kuo in the rotation while choosing to use Billingsley in a smaller role - and, given the strength of their bullpen, a relatively low-leverage role. I fear they would decide that Kuo only has value in the rotation, and conclude that Billingsley is as valuable in the pen as he would be in the rotation, when in reality both of these propositions are unlikely. It's obviously not a terrible problem to have, but there's no point in making rules for Kuo based on inadequate data, and I fear that the offshoot of such roles would be additional bizarre rules for Billingsley.
While I am curious to see whether Kuo really is much better as a starter, there's a good chance we'll never find out. Ideally, he will do so well as a starter that no one will ever think to try him in relief. Then again, he could flame out in the rotation this year, end up as a reliever and never being considered good enough to merit a starting chance again. He could also get tossed from the rotation for a poor stretch, catch fire when demoted to the bullpen, and we could end up with the rationalization that he was better in the pen all along - and, as with Gagne, we'll never find out if he could have made it as a great starter because people will be so attached to his relief performance. And unfortunately, given Kuo's history, we have to consider that a future injury will mean that we're about to learn even less about Kuo than the small record he has already accrued.