Basic Hitter Platoon Splits, 2002-2010

I’ve written about platoon skill generally and as applied to different players in the past. Today, I’d like to briefly take a look at general platoon performance as expressed in wOBA over the past decade or so (FanGraphs’ player pages have splits since 2002), noting some general tendencies and perhaps a couple of surprises.

As noted in my post from 2010 based on The Book’s chapter on platoon skill, the main thing we want to look at for a hitter’s platoon skill is how large the split is compared to his overall wOBA. This avoids certain logical absurdities and remains consistent with the fact that better hitters tend to have larger splits (in terms of straight wOBA). Thus, on each table I’ve given the hitter group’s wOBA versus left-handed pitching, right-handed pitching, and overall, along with the percentage (“Split%”) of the split (e.g., for lefties (wOBA versus RHP minus wOBA versus LHP) divided by overall wOBA). I’ve also included the percentages of plate appearances versus left-handed pitchers (“vLHP%”). In all cases, I’ve excluded pitchers and also the rare cases in which hitters decide to hit from the “wrong” side for whatever reason (this is sometimes done by switch hitters against knuckleballers, for example).

Let’s begin with the group that tends to have the largest and most persistent splits, left-handed hitters.

The seasons in which left-handed batters have done the best overall have generally been the seasons with the larger split. As mentioned above, we know that better hitters generally have larger splits on a “raw” level, but to see the percentage split generally (but not “perfectly”) correlating with better seasons for lefties is surprising. I’m not saying there is anything significant here, it may just be random variation. But it is interesting.

How about right-handed hitters?

As we would expect, right-handed hitters have a lower overall wOBA than left-handed hitters due primarily to their having to deal with the harder side of their platoon more often. They have been facing left-handed pitching a bit more often than have left-handed hitters. As with left-handed hitters, the size of the split generally correlates with the overall performance of the group. And, of course, right-handed hitters have much smaller splits. Uh, wait a minute…

What the heck happened in 2007? I have no idea. I’ve checked my query a few times, and get the same result: right-handed hitters had a slightly bigger split than left-handed hitters in 2007. Perhaps I (or someone else) can take a look more closely to see if there’s any specific cause or if it’s just a random occurence.

Finally, let’s take a look at switch hitters.

A negative percentage means that the switch hitters hit southpaws better that season. There is a fair bit more variation in switch-hitter platoon skill than either lefties or righties, which is why it doesn’t take as many plate appearances to establish that skill. As we see here, the splits are generally pretty small overall, which would tend to support The Book’s finding that most switch hitters are helping themselves out by hitting from both sides of the plate. Only in 2002 did switch hitters have a larger split than right-handed hitters, and that was the smallest split for righties in our sample.

Let’s compare the overall wOBAs for left-handed, right-handed, and switch hitters since 2002 in one final, indulgent graph.

This doesn’t have to do as much with platoon splits as with batter handedness in general, but is still interesting. We generally expect left-handed hitters to do better than right-handed hitters because lefties usually have the platoon advantage. What is interesting to me is that switch hitters, despite always having the platoon advantage, have usually hit worse as a group than even right-handed hitters, at least in the last few seasons. At the moment, I haven’t looked to see if this is just for this period or not. Is it he positional distribution, some other cause, or just random variation? But that’s a topic for future research…