In addition to that, usually for animation movies they do the voices first and make the animation to match. For comedy headliners, one might be able to recognize the actor from animated facial expressions, timing etc.

I am in no position to judge if that is true for Shrek.

(BTW, the German word for fear is Schreck [not a perfect translation, but the same spirit], yet I never made the connection mentioned in the article. Cool!)