The reason chimpanzees do so much better on the pull test, is leverage. (I learned this in physical anthropology class at Ohio State.) Their muscles are attached to their bones farther from the joint than in humans. This gives them greater leverage, therefore more force. However, the speed is reduced proportionately. So they're no good at throwing.

Bottom line: if you get into a beef with a chimp, don't wrestle it. Throw rocks at it from a safe distance.