November 27, 2012

Skewed Left

Year of the Right-Handed Hitter

by Zachary Levine

It was right around when my MVP ballot got six names deep on the path to a most difficult 10 that I realized what was missing. Where on this list of the National League's best were my people?

Didn't you put Ryan Braun second? He's one of your people.

No he isn't. Well, yes, he is one of my people, but I'm not talking about that kind of people. I'm talking about left-handed people. Where were all the lefties among the league's best hitters?

It wasn't just the National League, where the Most Valuable Player conversation centered around four names—the right-handed-hitting Buster Posey (my choice), Braun, Andrew McCutchen and Yadier Molina. The much louder debate in the American League could be framed as conventional vs. more descriptive statistics, acceptance vs. ignorance of defense, or simply a guy vs. another guy: Miguel Cabrera vs. Mike Trout. Any of those ways, it was righty vs. righty with fellow righty Adrian Beltre finishing third.

If 2011 was the second coming of the Year of the Pitcher—and it sort of was given this year's small hitting rebound—then 2012 could be classified in the moment as the year of the right-handed hitter.

But is this part of a growing trend toward that batter's box or more of an isolated season at the top end of the talent spectrum?

To dismiss this right away, the game—at least the batting portion of the game—is not getting more right-handed. If anything, it's gotten more left-handed in recent decades.

The percentage of plate appearances taken from the left batter's box, which includes left-handed hitters and switch-hitters batting lefty, has gradually increased over the last 40 years, with a few of the percentages isolated here.

Year	Lefty PA
1972	36.4%
1982	40.1%
1992	41.6%
2002	42.8%
2012	43.7%

Meanwhile, the percentage of those plate appearances with left-handed pitchers on the mound has not shown much of a trend at all, with the same years isolated.

Year	LHP PA
1972	30.5%
1982	30.1%
1992	30.8%
2002	25.1%
2012	29.8%

Given the significant advantage of facing the opposite-handed pitcher more often (and the much less significant advantage of being closer to first base) left-handed hitters have consistently put up better numbers than right-handed hitters. That gap is closing, however, as right-handed hitters overcome their disadvantage to pull nearly level.

Our True Average statistic has weighted outcomes by value, accounting for ballpark and league factors and normalizing to a .260 MLB-wide figure since 2000. It has not seen the two sides as close to even at .260 as they were this year.

Year	LHB TAv	RHB TAv
2000	0.266	0.258
2001	0.269	0.255
2002	0.269	0.254
2003	0.265	0.257
2004	0.268	0.256
2005	0.265	0.257
2006	0.266	0.257
2007	0.264	0.258
2008	0.266	0.258
2009	0.267	0.257
2010	0.265	0.258
2011	0.263	0.258
2012	0.263	0.259

What is actually happening starts to become clearer when isolating batters against pitchers of certain handedness.

It’s not so much that right-handers are making up ground because of anything they're doing as it is that lefties have been neutralizing other lefties. Just look at the TAv figures for lefties against lefties since the turn of the millennium.

Year	Tav
2000	0.253
2001	0.257
2002	0.253
2003	0.25
2004	0.255
2005	0.249
2006	0.244
2007	0.247
2008	0.248
2009	0.249
2010	0.249
2011	0.241
2012	0.237

Expressing these figures with more traditional stats, major-league left-handed hitters batted .232 and slugged .353 against left-handed pitchers this year. In the admittedly higher-offense environment of 2000, they batted .261 and slugged .407, and TAv shows a significant drop even when adjusted for era.

Within the age of specialization that predates this chart and will long outlast its patron saint Tony La Russa, bullpen specialization specifically for lefty-on-lefty matchups is on the rise. The 2012 season saw a new record with 697 left-handed relief appearances lasting exactly one batter, up from 584 such outings in 2000. Hitters—predominantly left-handed—had a ghastly .223 on-base percentage in those one-batter pitching appearances, which helps explain the overall downturn in lefty-on-lefty numbers. Teams are finding room for pitchers who can neutralize left-handed hitters, but righties are seen more as generalists—closers, long men (such as they are nowadays), and traditional setup men.

Twice in the last six seasons—2007 and 2011—the platoon splits have fallen under Simpson's paradox. That amusing and at times confusing logical conundrum occurs when two comprehensive samples of a population each exhibit a behavior trending in one direction, yet the whole trends in the other.

In those years, right-handed hitters fared better than left-handed hitters against same-handed pitchers and against opposite-handed pitchers, yet lefties overall were superior.

vs. same-handed pitchers
LHB: .241
RHB: .251

vs. opposite-handed pitchers
LHB: .268
RHB: .271

vs. all pitchers
LHB: .263
RHB: .258

It's much less confounding when you account for the fairly obvious fact that there are just more right-handed pitchers to face.

And in 2012, saved from Simpson's paradox only by a tie in one of the categories, lefties outperformed righties for another year as they should, but the gap is almost down to nothing thanks in part to the top two percent.

Oh, and as the topper to the year of the right-handed hitter, for the first time since 1992's Phil Nevin-Jeffrey Hammonds-Chad Mottola-Derek Jeter superfecta, the top four position players in the 2012 draft—Carlos Correa, Byron Buxton, Mike Zunino and Albert Almora—all hit exclusively right-handed.

Zachary Levine is an author of Baseball Prospectus. Follow @zacharylevine
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