This topic deserves more attention, and I'd like to get into it sometime soon. But since it was mentioned in The Miami Herald today, I thought I'd mention it: Luis Castillo pounds left-handed pitchers (when he hits right-handed) and is an average to below-average hitter against right-handed pitching (which is when he hits left-handed):
There's been talk for years that Luis should consider giving up switch hitting. He'd lose the advantage of being a step closer to first against right-handers. But that difference would (theoretically) be made up for by a higher batting average - though it won't be as high as the mark Luis posted from the right side of the plate this season.
This is an interesting topic. I'll get into the math of it eventually. If you've already thought about it, feel free to share. Or, share even if you haven't thought about it before.