Perfect Game

Randy Johnson threw a perfect game last night. I was struck by the rarity of this baseball event, forgetting the small difference between no-hitters and perfect games. If a no-hitter happens as often as a lunar eclipse, then a perfect game happens as often as the planets align.

My youngest brother used to let the computer simulate dozens (hundreds?) of baseball games. I remember him scanning the resulting box scores one evening, and exclaiming that in one of his simulated games, a pitcher threw a perfect game!