Takeaway is roughly: those observing the pitch expect it to be moving in one direction, and it often is moving in a different direction, giving the illusion of

Takeaway is roughly: those observing the pitch expect it to be moving in one direction, and it often is moving in a different direction, giving the illusion of a sudden change of direction. So the knuckleball is unpredictable, just not in the way that it appears to be.