Growing up, it all seems so one-sided ...

Left-handers were always something of an oddity at school. They sometimes had to have special seating arrangements. They had to have special equipment. They threw weird. And so on. On the playground, it was rare to see a lefty. In professional sports, not so much. Especially in baseball.

            There is a premium on left-handed talent in baseball. This exercise is mostly focused on hitters, though southpaw pitchers are, too, coveted like workers who speak (or think or even see) another language.

            A person is usually left-handed when the right side of their brain is more dominant than the left. The right hemisphere of the brain controls the left side of the body and deals with images and the connectedness of things, correspondences and resemblances. So left-handed people are often particularly good at art, music appreciation, and facial recognition. While right-handers might be better at logic, lefties would probably be able to imagine how a figure would look if its orientation in space were changed.

Think curve ball. Which defies logic.

Or sliders low and away. I'm not ruling out brain damage, but maybe there is at least one other explanation for why Sal Perez, who is right-handed, inexplicably flails at outside pitches in the dirt, failing again and again to recognize breaking balls. (He can catch a curve or slider because he knows it's coming.) Maybe Salvy is too left-brained?

Just because a person is left-handed doesn’t mean they see any better than anyone else. But they probably do see things in a different way than their right-handed counterparts do. This can be a very good skill to have. The majority of baseball players considered to be great hitters have been left-handed batters (and were presumably born right-brained?), though some threw from the right side: Babe Ruth, Ted Williams, Stan Musial, Mickey Mantle (batted from both sides), George Brett, Tony Gwynn, and so on.

While the right hemisphere of the brain is busy with lots of complicated things, it is responsible for processing much more visual (sensual?) information than the left hemisphere, which is dominant in most people and processes math and language as well as controlling plenty of common sense stuff.

            It follows that most people who analyze baseball are fairly left-brained and right-handed, or normally balanced. People who play it are more likely than the general population (according to me) to have a dominant right hemisphere and, therefore, are better equipped for seeing a baseball and hitting it left-handed. In short, hitting is mostly seeing. 

*Ewing Kauffman, the great Royals owner who died in 1993, had a notion that eyesight was a very important factor in deciding what players to draft to play baseball for his team. This should have been obvious, but nobody had ever really thought to evaluate eyesight as an official, quantifiable “tool” like home run power or even the ability to take walks. A hitter either had a good eye or he didn’t. According to Art Stewart's book, Kauffman hired a specialist to create a baseball-specific eye test and later shared the proprietary information with the rest of MLB. Kauffman wasn’t a scout and didn’t really care if a prospect was left-handed or right-handed. But as an owner who was investing a lot of money, he damn sure wanted to know how well a player could actually see a certain pitch that was coming from either side of the mound. And seeing (really seeing) and reacting to a 100 mph fastball or a nasty breaking pitch is a super-human skill.

P.S. Good left-handed batters generally crush right-handed pitching (and the majority of hurlers are still right handed). But they do tend to struggle, on average, with left-on-left match-ups. Line of sight is important for batters from either side -- hence switch hitters, pinch hitters, and pitching changes.

2S. None of this is supposed to be innuendo or some kind of sick bisexual joke. 

3P.S. Lots of left-handed hitters throw right-handed (almost never the other way around), which is probably due to Darwinian advantages or something (or, more likely, due to the fact that throwing left-handed across the infield diamond, against momentum, just doesn't fly in baseball). Regardless, hitting is seeing; throwing is not. 

4P.S. In life, some people become right-handed to overcome disadvantages. In baseball, some people become left-handed hitters on purpose, which throws some of my theories out of whack. There are incentives in being a left-handed hitter -- if you can swing it, so to speak. For instance, a left-handed batter is at least one step closer to first base.

5P.S. According to my logic, right-handed batters with good eyesight should be better at hitting fastballs than breaking balls (not going out on a limb there). Left-handed hitters should be better in general. Would-be hitters with bad eyesight (from either side) would just be bad hitters.

6P.S. More left-handed pitchers are always needed to mitigate the advantages of left-handed batters. 

7P.S. Oliver Sacks, notably, has written popular (non-baseball) books about interesting clinical cases in neuroscience.