The answer's in the numbers

With the theory that lefties hit better than righties against righty pitchers and vice versa, platoons make sense.

Originally Published: February 9, 2004
By Rob Neyer | ESPN.com

Revisiting last Friday's column while hoping that we haven't seen the last of Robb Nen ...

    Rob,

    Your article on platoon splits was interesting, and led me to wonder if anyone has done the same sort of analysis for pitchers? I had always assumed there were some (even many?) pitchers that were absurdly more effective against hitters on one side of the plate than the other. Has this also been overstated?

    -- Bryce

Oddly, I don't recall seeing the same sort of analysis for pitchers. Which certainly doesn't mean nobody's done it, though I assume that even the most skeptical of sabermetricians would assume that a right-hander who throws sidearm curveballs is tougher on right-handed hitters than left-handed hitters.

More fundamentally, there is presumably a real difference between pitchers and hitters. Pitchers are all trying to accomplish the same thing, of course -- retire hitters -- but they do so in vastly different ways. A fastball pitcher's not the same as a curveball pitcher who's not the same as a sliderball pitcher who's not the same as a knuckleball pitcher ... and then there are all those different arm angles.

I know, I know ... those are theories, not facts. The facts are tough to tease out of the theories, though. Aside from the fact that pitchers employ different styles, you can't simply look at pitchers' statistics against left- and right-handed hitters, because (for example) some left-handed pitchers are (apparently) so tough on left-handed hitters that managers are loath to let any but the best left-handed hitters face these particular southpaw pitchers. Which makes those left-handed pitchers' numbers look less impressive against left-handed hitters than they might otherwise be.

Getting back to the right-handed hitters for a moment, I could have done a better job in Friday's column explaining the central thesis. If I had, I wouldn't have received messages like this one ...

    Rob,

    I'm not sure I fully understood your Eric Karros column. When you say platoon splits would be roughly the same for all (or nearly all) players given enough time are you saying that there is essentially no difference to hitting against righties and lefties?

    Because that seems to be the conclusion and if that is the case then does it follow that, ballpark factors aside, teams should not care which side of the plate their hitters bat from? And if that does not follow, why not?

    I consider myself very open-minded when it comes to baseball's conventions, but I am having a hard time accepting that, given enough at-bats, Timo Perez's numbers against righties and lefties would be about the same.

    -- Bill

Let me be very clear about this: Yes, there most certainly is a difference to hitting against righties and lefties. As a group, right-handed hitters fare roughly eight percent better against left-handed pitchers than they do against right-handed pitchers.

With me so far? Of course, because that's the easy part. Now, here's the hard part ... All (or almost all) right-handed hitters innately have that 8-percent edge against left-handed pitching. No matter what a right-handed hitter did last year against left-handed pitching, or even over the last five years (or more), it's highly likely that he's innately 8 percent better against lefties than righties.

I know it doesn't make any sense, and you can find plenty of examples of players who seem to "prove" otherwise, but all those examples are within the range of what we would expect to find. They're called "outliers."

By the way, one thing I neglected to mention in Friday's column: as Steve Treder noted in a Baseball Primer discussion thread that includes technical discussions of all this, "there is far less variation in platoon split among major league RHB than among major league LHB. It is an empirical fact."

Why would this be? Here's one theory (not my own, by the way) ... Growing up, right-handed batters face mostly right-handed pitchers, and so they get used to them. When they reach the minor leagues, it's not easy to hit a curveball or slider thrown by a right-handed pitcher ... but at least they've seen those pitches before. But there are very few left-handed pitchers in Little League, and few even in high school. So when a left-handed hitter enters professional baseball, having already spent many years learning to hit, he will probably have faced very few left-handed pitchers. And very few good left-handed curveballs and sliders.

As I said, it's just a theory. But it's the best theory I've seen.

Speaking of left-handed hitters, it's commonly said of great left-handed hitters -- the so-called "pure hitters," the ones with high batting averages -- "It doesn't matter to him who's on the mound. He hits right-handers and left-handers equally well."

Actually, that's not said as much any more because the statistics are so readily available. But when I was a boy I heard it all the time about George Brett, and it was also said about Rod Carew and Wade Boggs and Tony Gwynn, among others. Well, here are the batting averages for this quartet against righties and lefties:

                  vsRHP  vsLHP  Ratio
Carew, 1967-1985   .335   .312   1.07
Brett, 1973-1993   .318   .280   1.13
Boggs, 1982-1999   .341   .297   1.15
Gwynn, 1982-2001   .354   .325   1.09

(The source for all pre-1993 seasons is Retrosheet, and doesn't include 198 games of Carew's career because they haven't been posted yet. The post-1992 data was lifted from various editions of the STATS Player Profiles books.)

No, we cannot draw some general conclusion about left-handed hitters from the statistics of just four members of the group. I just wanted to point out that nobody, not even the greatest hitter, is immune to the natural platoon disadvantage.

Sometimes I wonder if, and worry that, perhaps we might already know nearly everything worth knowing about baseball statistics. But then I run across something like this, and I am heartened. Because if so many of us still don't know something fundamental about something so basic as platoon differences, then obviously there is still a great deal for us to learn.

Senior writer Rob Neyer writes three columns per week during baseball's offseason. This spring, Fireside will publish Rob's next book, "The Neyer/James Guide to Pitchers" (co-authored with Bill James); for more information, visit Rob's Web site. Also, click here to send a question for possible use on ESPNEWS.

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