Hey, left is right... well, at least as far as throwing and batting is concerned. ;)
As for why it's like that in baseball, that being lefthanded is an advantage, I'd love to find out why. Never seemed to help me. 'Course, the fact that I su.cked when I played might have had a little something to do with that too.
"But RIGHT-HANDED BATTERS STILL HIT BETTER AGAINST LEFTIES THAN RIGHTIES."
More left handed batters do worse against left handed pitchers than right handed batters against right handed pitchers. most teams try and balance LH RH in their lineup, when a lefty pitches, they go for a RH heavy lineup to combat that.
Right handed batters get more time to get better against right handed pitchers because they see the 75-85% of the time. Whereas lefties only see left handed pitchers 15-25% of the time, which is not enough. the RH to LHP advantage is in the ability of the hitter to see the pitch/spin on the ball earlier than against a RHP.
The only possible reason i can figure is that lefties bat worse against lefties than righties against righties, while opposing dexterities are about equal. A reason behind this would be that lefties see far more righties, and are unused to facing a southpaw, while righties get used to seeing that many righties and learn to hit against them more effectively. I dont know the true comparison between left-left and right-right though, so lets just say they are the same, as they would be theoretically. Pickoffs are also irrelevant. Kenny Rogers is the all time PK leader; his career ERA is 4+, nuff said.
There is nothing special about a lefty throwing compared to a righty, it just defies the laws of physics. If two pitchers were the exact same in every aspect; windup, throwing style, etc. but had opposing dexterity, the only difference would be which side of the plate the ball comes from. Batters can see the release point of an opposite handed pitcher, hence the advantage. Despite this, people think that a southpaw is something special and is automatically better, they are not. If two pitchers of opposing dexterity had identical results in every stat for the season, with identical splits between the dexterity of batters, which one is more valuable? What if the amount of lefties and righties faced were equal, and they posted splits inversely identical? The answer is neither, since both are equally effective against the competition. The question that should actually be asked is who is a better gain for the team, based on age/salary/reliability etc.?
And that is just in theory. In todays game, you have southpaws who have lefties hitting below the mendoza line and righties hitting .300, while others have .230 and .235 splits, and even some who have the inverse of the first example. The same is true for Right-handers. So, unless you are looking for a specialist in the bullpen, the dexterity of a pitcher should be null when it comes to evaluation, and only statistical measurements should have value.
"the dexterity of a pitcher should be null when it comes to evaluation, and only statistical measurements should have value."
Too bad (not really) that will never happen. There are, and will always be lefties that can't hit lefties.
"I've heard many times that a pitcher is better than another one because he's a left-hander and the other isn't, and stuff like that... Well, first of all, why is it an advantage?"
Well it can be an advantage if the home ballpark of that lefthanded pitcher favors left handed batters. That way, an opposing manager would most likely try and stack his lineup with lefties. But an effective lefty can keep the ball tailing away from lefties in an attempt to limit their ability to pull the ball. And then when they face righties, them pulling the ball would less dangerous because the big part of the ballpark would be in that direction. And I'd imagine that going the other way with power for righties, or anybody really, would be more difficult.
But I do think that the importance of having a lefty is a bit overblown at times.