I remember seeing a demonstration on Ripley’s or some such show that proved the ball does actually curve. A barrier was placed between the pitcher and catcher such that only if the ball curved could it make it over the plate.
Link to the article: Do curveballs really curve?
EInstein once offered that the baseball doesn’t curve,
DiMaggio said"Give him a bat"
I can’t tell if you’re kidding or not, but if not, I’d like to see a cite for Einstein claiming baseballs don’t curve.