Matt Cain pitched a perfect game for the Giants this week. Some people have been wondering “WTF? Why are there so many no-hitters and perfect games recently?”
Overall league batting average is down this season, compared to last season, by about 0.005 to 0.01.
It’s a nonlinear relationship. If overall batting average decreases by a little, the odds of a no-hitter or perfect game increases dramatically.
Suppose that overall league batting average is x. Then, the odds of a no-hitter are approximately (1-x)^27. If you want to calculate the odds of a perfect game, use on-base percentage instead of batting average.
Using that formula, here are some details
|League Batting Average||Odds of a no-hitter|
Notice that a small decrease in batting average leads to a huge increase in the odds of a no-hitter. If overall batting average decreases from .270 to .260, then the chance of a no-hitter increases by nearly 50%!
Usually, when batting average decreases, MLB will change the rules to favor batters, either by lowering the pitcher’s mound or shrinking the strike zone. Until then, there will be more no-hitters, due to a decline in batting average.
There’s been an “explosion of no-hitters” recently, due to a decline in overall batting average. It’s a nonlinear relationship. A small decrease in batting average leads to a huge increase in the odds of a no-hitter