One topic David and I were considering discussing on yesterday afternoon's podcast was Kevin Correia's home-road splits and whether there's any advantage to be gleaned from moving him into a home-road platoon with another starter.
This sounds, on the surface, like a cockamamie idea, and I'll just go ahead and spoil the ending by saying that that's what I think it actually is. But I want to address it here because 1) it keeps coming up over and over, and 2) the Pirates don't have the luxury of being able to dismiss unconventional ideas as cockamamie. If there is something to this home/road thing, they need to be the sort of team that notices and exploits it, because they don't have advantages like that handed to them very often.
So, Correia's home/road splits in 2011:
Correia is off to what would appear to be a similar start this year, with two good starts on the road. (He hasn't yet pitched at home.)
Obviously, Correia was much better on the road than at home last season. But we shouldn't automatically assume there's a reason for that if there isn't an obvious one. PNC Park is probably better for lefty pitchers than for righties, but there's no reason it can't be a hospitable environment for a righty starter. Correia doesn't appear to be poorly suited to the ballpark. I suppose there's also the possibility that he freaks out at the sound of people cheering for him or something, but that seems so odd that it's not even really worth considering. Maybe his bed at home is less comfortable then hotel beds on the road? If there's an explanation, we have to do some pretty serious grasping to find it. So what is it? If Correia's home-road splits are the result of his true talent rather than simple variance, then why is that the case? I'd like to have at least some idea before I acted on it.
In an attempt to extract some of the variance, let's look at some of Correia's advanced numbers from 2011.
Ah, here we go. This is sort of a mixed bag, in that it shows that Correia gave up a bunch more line drives at home, and I don't have a good reason for that. He simply got hit harder, which surely explains some of the disparity in his BABIPs between home and road. Note, though, that a lot of it is simply that more home runs flew out of PNC Park than elsewhere. (Correia actually allowed a lot more fly balls on the road than he did at home, and way fewer of them left the park.) There wasn't much of a meaningful difference in his strikeout to walk ratio. Correia was also much better at preventing runners on base from scoring on the road than at home (81 percent LOB% vs. 57 percent), and there isn't much of a reason to think that's meaningful.
The picture is muddled, but it looks like at least some of Correia's home/road difference was the product of factors that probably don't have much to do with Correia's actual home/road skill, such as the vagaries of fly balls turning into home runs, and Correia doing a much better job keeping runners from scoring. The former, in particular, is a big part of the reason his home xFIP is actually better than his road xFIP.
That doesn't explain why Correia demonstrably got hit harder at home than on the road, but Correia only allowed 98 line drives the whole year; that he allowed more of those, even a bunch more, at home than on the road doesn't necessarily mean a whole lot, statistically. In the absence of a coherent reason to explain the difference, and given the likelihood that variance has at least something to do with it, I'd just as soon ignore it.
I certainly wouldn't act on it by, for example, moving Correia and James McDonald into a home/road platoon, as Bucdaddy recently proposed. For one thing, the upside in such a move is small, since Correia is a veteran and isn't under contract next year. For another, Correia really isn't good enough to warrant that kind of extraordinary treatment. Also, the downside is great -- not so much for Correia, but for the pitcher he'd be "platooned" with. All the Pirates' other starters (except possibly Erik Bedard, who I don't think anyone wants to mess with) have some chance of being with the Pirates in a starting role beyond 2012. If you'd like to change their role from "starter" to "starter sometimes, but not during road trips," you'd better have a pretty good reason for it. And finally, moving Correia and another pitcher into a home/road platoon would complicate the Pirates' bullpen decisions. There's no good reason to do this. Let's just leave this alone.