Here’s an AP article once again arguing whether curve balls really break that sharply or instead are an optical illusion. Wasn’t this question conclusively settled in the 19th Century?
In this article, the scientist argues that, while curveballs do break, they don’t break as sharply as hitters seem to think. He thinks it has to do with the way see the curve as it comes toward them.
The writer of the article (Dave Campbell?) interviewed HOFer Mike Schmidt, who has some interesting things to say on the subject. It’s worth reading the article if only for Schmidt’s comments. Schmidt points out that over pitcher’s curve ball is a little different based on arm strength, grip, amount of spin they put on the ball. Some pitchers have big arcing curves, while others (particularly, the hard throwers) have sharper break.
As someone who’s seen plenty of curve balls on TV, it’s clear that guys who are throwing the big overhand curve ball really well get late sharp break down on their curves. The downward breaking curves probably break more sharply than curves that have more sweep from one side to the other because they get a boost from gravity on the curve that breaks more downward than across. It’s hard to imagine that what I’m seeing on TV for the last 30 years is any kind of optical illusion.