A Wired post (pimping the book Scorecasting) tells of a book in which, among other things, someone crunched the numbers of a million or so MLB pitches and found that the umpires made the right call about 85% of the time.

When the pitches were in the corners, though, they got it right about half the time. Half the time is statistically close what you'd get if you guessed without even looking.

I'm not sure we should mechanize or otherwise automate strike calls, but something should be done. I know it certainly feels like they get it wrong a lot more when my team stands to gain from the right call.