Some Observations and Questions on Handedness

Humans have had a long and storied relationship with tools. From rocks and sticks to pocket knives and sonic screwdrivers, we have depended on tools to make our lives easier and more efficient. But a recent study shows that our use of tools might also have a lot to do with how we use our hands. A study from the University of Sussex shows that our (humans’) penchant for right-handedness has a lot to do with what part of our brain thinks about how to manipulate tools. Our left hemispheres do most of the heavy lifting when it comes to how we interact with tools. This is how humans and their close cousins came to be right-hand dominant species. This also could help explain how humans developed speech, as the constant working of our left hemispheres — the side responsible for speech — caused them to get stronger.  However, the study shows that this dominance only manifests when the subjects were dealing with inanimate objects. When dealing with animate objects — like other animals or themselves — no real dominance was shown.

There are a lot of studies about handedness in humans — how it affects their personalities, relationships, careers, etc. From what I found, there really aren’t many on just how many people are left-handed. Perhaps that has to do with the fact that they don’t pass out a lot of grant money for just counting stuff. However, there seems to be a general consensus that about 10% of humans are left-handed. By left-handed, of course, I mean left-hand dominant. Many people fall somewhere in the middle along the Edinburgh Handedness Inventory.  I’m right-hand dominant, and very much so. I do everything I can think of as a righty, though I’ve been told I sweep like a lefty when curling. I know many people, and you may too, who switch it up, though. They may write and eat left-handed, but throw and bowl and play pool right handed. They may use their right to pick up the phone, but their left to open a door. Again, a lot of it comes down to what we’re interacting with. This is the point when I talk about actual baseball.

This started — like a lot of baseball writing, trust me — with an incorrect hypothesis. It seemed to me that there were less switch hitters than there were even a few years ago. So I ran the numbers, and I was wrong. Pretty badly wrong. So I expanded it out a little. I looked at the percentage of plate appearances that went to batters that the Retrosheet database defined as switch hitters from 1961 to now, commonly known as the expansion era.


This is more interesting. It seems as if there were very few switch hitters in the early 60s, and their heyday fell between the mid-80s and mid-90s.  They’ve tapered off a bit since then, but are still in higher numbers than even the early 80s. So, if all these plate appearances are going to switch hitters, from whom are they taking them?


It looks like they are taking them from right-handed hitters. In fact, there has been a pretty steady decline in right-handed batters since 1961, an almost 12% drop in fact. But why? If 90% of the population is right handed, why do right-handed batters only get half of the plate appearances? Are there just fewer righties in the league? Well, maybe.

Available data does not include what hand a player defines as their dominant hand. We can only deal with game data. Because of this, we have to make some assumptions. One of those assumptions I’m going to make is that the hand a player uses to throw is their dominant hand. It seems like a fair assumption, accounting for all but the truly ambidextrous. With that in mind, there seems to have been a slight drop in overall righties in the league.


But that’s only about a 5% drop, so it must be something else. Perhaps this is an indication that more naturally-right-handed players are focusing on switch hitting or hitting lefty. This makes a little bit of sense. Right-handed pitching has seen a bump over the past 20 years or so.


So it seems reasonable that GMs and managers are looking for players that can hit from the other side. However, right-handed throwers — that is to say, players that catch with their left hands — are still preferred or required in many positions such as third base, shortstop, and catcher. So a righty that can hit lefty might have an advantage.


Since 1961, pure right-handers have been in decline while right-handers who can hit from the other side have risen — though the exact way this hashes out has fluctuated. Are righty-righty players discriminated against? Do righties who can hit from the other side have a better shot of reaching the big leagues? Are young right-handers being taught to hit switch or lefty to help their chances in getting drafted or getting a scholarship to college? These are all questions I don’t have answers to, hence the title of this article. But it does seem that baseball players are continuing to break their natural inclination to use their right hands to manipulate tools. But is batting “left-handed” even a pure form of left-hand dominance? I mean, both hands are on the bat. Is it easier to get a right-hander to bat from the other batter’s box than it is to, say, teach them to write or eat or throw left handed? Man, it’s days like today I wish I were a neuroscientist.

The truth probably lies somewhere in the middle of all these questions. Natural lefties may be looked on more favorably. Natural righties may be learning to hit left handed. This issue — like a player’s clubhouse contributions or a managers true effect on a team — deals with sociology, psychology, and biology in a way we can’t boil down with simple game data. Maybe humans are evolving into some super race that can use both hands at will, and baseball is at the forefront. Or maybe the fact that we don’t make anything by hand anymore has led to a reduced need to rely on our left hemispheres. Whatever the case, we can put this in the bin where a lot of baseball research goes. We know that something is happening. We’re just not sure why.

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David G. Temple is the Managing Editor of TechGraphs and a contributor to FanGraphs, NotGraphs and The Hardball Times. He hosts the award-eligible podcast Stealing Home. Dayn Perry once called him a "Bible Made of Lasers." Follow him on Twitter @davidgtemple.

54 Responses to “Some Observations and Questions on Handedness”

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  1. jim S. says:

    I read somewhere that since a person’s eyes are of different strength, learning to bat LH (after beginning as a RH batter) might lead to a considerable improvement. I wish I could remember why, but I can’t. But I think it had something to do with the right eye (as a lefty batter) picking up the ball first. I began switch-hitting when I was 15 and my average went up 100 points.

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    • Stuck in a slump says:

      This is true, when I first joined the military they had me shooting right handed because I identified as a righty. Eventually as my shooting got worse one of my instructors asked which eye was better, my left or right. When I answered my left he had me shooting from that side and while it took a little bit of adjustment, I still shot better right off the bat.

      I also had friends and family wondering what I was doing when I first picked up a pool cue and started shooting left handed when I was 7 or 8. I didn’t even know why, it just felt more natural. Given my early childhood problems with my right eye though, I wonder if I wasn’t just naturally adjusting.

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    • tz says:

      I remember reading that Ted Williams regretted that his left eye was his stronger eye, since he would have had much more success if his right eye was stronger (as the lead eye).

      Now imaging adding 100 points to his average….

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    • Sam Horwich-Scholefield says:

      I think you may be right. While about 20% of hitters are naturally left handed, less than 15% of switch hitters throw left handed (min. 450 PA in 2013). Smoak, Beltran, Nava, Swisher, and Melky are the only major league regulars I can think of.

      ‘ve done some research on BB/K splits for switch hitters, and although the sample size is small for natural lefties, it appears that being a being a switch hitting righty is generally more advantageous for this stat than being a switch hitting lefty, at least when comparing to league average. If we take BB/K rate to be a proxy for knowledge of the strike zone, then you could make an argument that hitting from the left side gives a batter a ‘better look’ than hitting from the right side. Natural left handers may see less of an advantage to switch hitting than their right handed counterparts.

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    • BenS says:

      Eyes work differently than the rest of the body when it comes to brain hemisphere. Per Wikipedia:

      “Visual input follows a more complex rule: the optic nerves from the two eyes come together at a point called the optic chiasm, and half of the fibers from each nerve split off to join the other. The result is that connections from the left half of the retina, in both eyes, go to the left side of the brain, whereas connections from the right half of the retina go to the right side of the brain. Because each half of the retina receives light coming from the opposite half of the visual field, the functional consequence is that visual input from the left side of the world goes to the right side of the brain, and vice versa. Thus, the right side of the brain receives somatosensory input from the left side of the body, and visual input from the left side of the visual field—an arrangement that presumably is helpful for visuomotor coordination.”

      Batting left handed means that the left half of each eye is picking up the ball which goes to the left hemisphere of the brain which controls the right hand. If having one eye being stronger than the other affects batting potentially that much than maybe eye dominance plays as big a role as hand dominance in determining which side of the plate a batter will be more successful from.

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    • FanGraphs Reader says:

      Could you please provide a link to the article that shows that your “average went up 100 points”?

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  2. JuanPierreDoesSteroids says:

    Are righty-righty players discriminated against?

    Please don’t get Alex Remington started.

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  3. Chickensoup says:

    I don’t think that righties are discriminated against per se, but I think the data would probably show that because lefties have a natural matchup advantage against righties, that a left handed hitter has an advantage, even if it is slight, making it to the big leagues. I don’t have a copy in front of me, but i believe this was even covered in “The Book”

    Basically: Hitters gain an advantage when facing opposite throwing pitchers. If 90% of the human race throws right, then a large percentage of pitchers would be righty. Thus it would follow that overall numbers for a lefty hitter would be slightly inflated by the batting advantage of facing mostly right handed pitchers.

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  4. Jim Abbott says:

    It’s amazing how small the handedness split is for pitchers:

    ERA- Split by Handedness:
    One 99
    Two 100

    FIP- Split by Handedness:
    One 100
    Two 100

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  5. J6takish says:

    I always assumed that left handed players with strong throwing arms are usually converted to pitchers at a young age. As far as right handed players who bat lefty, hideki matsui and alex Avila come to mind. Matsui bats left handed because he was so much better at baseball than his brothers/peers as a child, he swung left handed in order to handicap himself enough to make the games fair. Alex avilas dad is an the assistant GM and taught alex to bat left handed to have a better shot at the big leagues

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    • Mr. X says:

      A lot of players bat L and throw R, it doesn’t mean they were taught that way. Curtis Granderson is another that comes to mind.

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      • Andrew says:

        lots of right handers bat left. It’s rare when a left hander bats right. Ex: Ryan Ludwick, Cody Ross, Jason Lane, Rickey Henderson

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        • Ian R. says:

          Well, that’s rare among position players. There are actually quite a lot of left-handed pitchers who bat right-handed, though I have no idea why. Does it make bunting easier?

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        • AC of DC says:

          In reply to Ian R: It may be that they are naturally right-handed and simply learned to pitch lefty, and are perhaps even more dreadful than normal pitchers batting when swinging lefty.

          Anecdotally, there have been several pitchers who were relatively decent hitters from the opposite side, but were required by their teams to hit same-handed so as to avoid exposing the pitching arm to incoming pitches, though at the moment only Doc Gooden comes to mind.

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        • jfree says:

          Ian — the reason pitchers bat from the opposite side is to protect their pitching hand. Ie keep it off the middle of the bat (in the strike zone) when they do bunt so it doesn’t get hit/broken. They aren’t really expected to make contact otherwise. My guess is that lefty pitchers are probably more aware of this at a younger age so more of them bat right than righty pitchers bat lefty. I changed in high school because if I broke my hand, there was no other position I was going to be allowed to play except backup OF.

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    • Joe Durant says:

      Alex Avila was a switch hitter and a pitcher until he reached college, where he stopped pitching became a lefty DH.

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    • jfree says:

      100% correct. There are only two generic positions a lefty is “allowed” to play — from Little League on. If you can throw well, you have to pitch because lefties aren’t allowed to play 3B/SS/2B/C. If you can bat, you are only allowed to play 1B/OF for the same reason. So lefties will end up as either Pitchers or 1B/OF. As players face better talent and body type itself begins to affect positions, then any lefty who is not a power hitter type will either become a pitcher or give up baseball (or maybe moved to CF if they are fast).

      The reason why natural righties learn to bat lefty is because there is a career advantage to being opposite-batted once pitchers (still mostly righty – though less so than the overall population) begin to throw breaking stuff.

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      • Ruki Motomiya says:

        I always wondered if lefties not getting to play 3B/SS/2B/C was a bad idea or not.

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        • Billy says:

          I think the physical complication of playing middle infield as a lefty would be pretty awful on high levels since the ball is hit to both sides so much. A lefty shortstop would have trouble getting anybody not named Bengie Molina or Kendrys Morales on a ball hit to the 5.5 hole.

          Third would only be a problem on balls hit to your right, as good footwork would allow getting into throwing position on balls hit to your left. But I could imagine this still being a problem on balls to your right. And bunting could be a nightmare.

          As for catcher, I think it has to do with tagging a runner who is approaching from your left. Throwing to third would probably also be a tad harder.

          Overall, I think conventional wisdom has this one right, but if it wasn’t for people asking questions like this, we would never find out what else we may be missing.

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        • Jim Price says:

          Yes it is. I’m a lefty and tried SS and C. SS was OK but you’re always doing a reverse pivot to throw to first so it probably gives the runner an extra step. C was awful, turns out you mess up the umpire’s positioning and most batters are RH and their head is right in the way of the throw to 2B (or even back to pitcher).

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  6. james wilson says:

    Lefties are no more than one-tenth of the population, probably more like one in thirteen, but they are represented in all athletics in far greater proportions than that. The lone exception is golf, and I expect there are many lefties there playing as righties.

    To my knowledge, all major league pitchers who have broken their arms pitching were left handed, which tells me that lefties are able to get more out of the same equipment than righties.

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    • Another FanGraphs Reader says:

      Lefties have an advantage in sports where opponents face each other. That would not be the case in golf.

      A lefty will be used to facing righties but not vice versa, so they have an experience advantage at very least.

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    • jfree says:

      I am a lefty who was taught to play golf righthanded from the start. Clubhouse pros inevitably say that it is “smart” for lefties to swing golf clubs from the right and “justify” it with “you’ll be really good if your strong side is pulling the club through the swing”. It’s complete nonsense of course — unless righties have been playing golf “wrong” since forever. But — when all you have is righthanded clubs, you better learn to swing righty.

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    • Bip says:

      I heard that Phil Mickelson, the one lefty-swinging golfer that comes to my mind, is right-handed and taught the swing left handed. I heard it was because learning to swing the hard way would cause him to develop better technique. I could see it, he may have had bad habits from the right side, but from the left he could basically develop a swing from scratch.

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  7. DrBGiantsfan says:

    The relative dearth of LH throwers is precisely the reason why Left Handed Relief Specialist AKA Lefty One-Out Guys AKA LOOGY’s are essential to teams with aspirations of winning the World Series. You need to have someone you can bring in and reliably retire LH batters in high leverage, late-inning situations.

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  8. krugerindustrialsmoothing says:

    wait, you curl? nice.

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  9. james wilson says:

    There is no relative dearth of left handed pitchers. They are insanely over represented, 28% of all innings in mlb. If there is not always one ready to go it’s because 43% of hitters are coming up from the left side, but only a third of them are true left handers.

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  10. pft says:

    The reduction in the platoon advantage that LHB’ers have had over RHB’ers is rather significant in recent years. From 33 OPS point advantage from 2000-2004 to 11 OPS points from 2009-2013.

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  11. jfree says:

    To the author — the reason righties have been “in decline” since the early 1960’s is not because of discrimination against righties. It’s because the “natural rate” of left-handedness in the male population is closer to 15-20% than to 10%. I would bet money that the reason it was lower than that in the immediate post-WW2 era is because war has always killed lefties in greater proportion than righties (has to do with exposure of heart/arteries – and “not fitting” in groups which means lefties end up on the flanks – and in modern war, machinery will always tend right-handed)

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    • siggian says:

      Could the rise in the natural rate of left handers be as simple as left handers are no longer actively discouraged from doing things left handed (in general)? And these left handers are now more willing to identify themselves as such?

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  12. John Carter says:

    I agree it is shocking there were so few switch hitters in the early and mid 60s, when two of its most famous hitters were: Mickey Mantle and Pete Rose.

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    • Bip says:

      What if that is the reason for the boom in switch hitters in the 80’s and 90’s? Some of those players probably grew up watching those guys, and as kids they want to do everything they do. Others may have been raised by dads who idolized them and taught their sons to hit like them.

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  13. Billy says:

    First off, are there any players who throw with their off hand? How many LHP are naturally lefty? I’d think almost all since doing something that requires the fine motor skills of hitting a gnat in the butt from 60’6″ would be tough to do with your off hand, but I might be wrong. I’d imagine almost no position players throw with their off hand and maybe only few pitchers.

    Also, I’ve had the following hypotheses and need to figure out a way to test them?

    Are righty hitters better athletes than lefty hitters since it takes better abilities to be a good hitter if you have the platoon advantage less often and still be productive? And what about lefty hitters who are natural righties, since it may take better “natural athleticism” to learn to hit from your off side and may indicate better natural ability? Switch hitters may be a similar beast. Also, I’d have to adjust for position since some positions like shortstop require more “athleticism” to play and may bias things. But at the same time, seeing if there are any differences between lefty and righty hitting players at C/2B/3B/SS in other areas of athleticism would be interesting too.

    But for sure, I could compare naturally lefty outfielders and firstbaseman to their naturally righty counterparts and their naturally righty but lefty hitting counterparts and see if there are any differences. But even then, maybe the righties who were selected to play other positions have some reason that affect my results. Ugh, this is complicated, but so interesting because of it. As for those weirdos who throw lefty but choose to bat righty (I’m looking at you Ryan Ludwick and Cody Ross. Why would you even do this?) I’ll just leave them out and worry about them later since I have no idea what the hell that might mean.

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    • Jim Price says:

      I would say no MLB players do this. Try throwing with your opposite hand. Then imagine being one of the top 1000 in the world doing that. No way. EVERY MLB player throws with their dominant hand.

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      • Bip says:

        It takes an insanely large amount of time to learn how to throw a baseball. So the hand you throw with is the hand you learned to throw with as a kid. Hyun-jin Ryu doesn’t throw with his dominant hand, but he sure didn’t learn to do that after already learning to throw with his dominant hand.

        I don’t think a person will necessarily be better at throwing with their dominant hand than with their off hand. I think that a person will be more likely to originally learn to throw with their dominant hand because it will feel more natural, but whichever hand you pick, it’s the time and practice that will give you ability.

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  14. Steve says:

    Looking at the Batting Handedness graph (#2), it looks like since the 1990s switch hitting has gone down slightly in favor of pure lefty batting, probably by righty throwers. I agree with you that the increase in lefty/switch has come at the expense of righty numbers.

    Perhaps righty children are being encouraged to bat left handed from the start more often now; I certainly would recommend trying.

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  15. Sivart says:

    A shoulder injury caused me to try batting LH for the first time in my 20s, and despite my contact rate going down initially, it was better in ever way – it even feels more natural. And I do absolutely everything else as a righty.

    That led me to start thinking that just grouping people as righties or lefties and trying to draw conclusions from those groups might not be the most predictive methodology.

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  16. brendan says:

    quite players bat lefty, throw righty (esp infielders who othewise couldn’t play 2B/SS/3B) – but not a lot bat righty, throw lefty; so you might not want to use throwing handedness that way, it might skew your results.
    e.g. eric chavez, brandon crawford, prince fielder, curtis granderson, chase utley, robinson cano

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  17. Bip says:

    Technically it’s not a human who relies on the sonic screwdriver.

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  18. Bip says:

    I know Hyun-jin Ryu is naturally right handed but was taught to throw with his left hand to give him an advantage as a pitcher. Madison Bumgarner, like Ryu, throws with his left and and bats right handed, so I wonder if he is the same way.

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