why does the author use the simile “Jake steps into the throw and chucks the ball like a middle tied to a tightrope wire”?

Answer 1

"A middle tied to a tightrope wire" is a physical sign circus performers use to tell them when they are in the middle of the rope, which is important because of how the rope behaves there. So when "Jake steps into the throw," he prepares to throw the ball, and then "chucks the ball like" that "middle." In other words his throw was perfectly centered.