Are curveballs just an illusion?

I saw this story on MSNBC and happened to click on a link within the story. I was fascinated. Maybe too much so, but I'll share with you and you can decided.

First, the story. The Associated Press (via MSNBC) published a story saying that curveballs may be nothing more than an optical illusions. Being a former baseball player, I was offended. I struck out on many pitches that seemed to "fall off the table." But the scientists making the claim in the story apparently put together an optical illusion on the computer that proves their point.

This is amazing (click on the pic below to experience it):

Is it true? My pride is still telling me no. I'm praying for a debunk here.