The Mishna (76b) taught that one of the people who is liable to receive a death penalty and would be killed by sword is a murderer. The Mishna gives examples of who would be considered a murderer and who would not. If someone held someone else under water or in a fire, he would be considered a murderer, but if the second person could easily get away, then he would not be considered a murderer. Similarly, if someone encouraged a dog or a snake to attack he would not be considered a murderer, although if he actually held the snake and caused it to bite then Rabbi Yehuda would consider that to be a direct attack, and he would be considered a murderer.
The Gemara brings a number of cases where it tests whether a person’s actions are considered to be a direct cause of death, which would make him a murderer in the eyes of Jewish law, or if what he does is only considered an indirect cause and he will not be liable to receive a death penalty. For example, when someone throws a rock against a wall and it bounces back and kills a person, Rava rules that it is considered to be a direct cause and the person who threw the rock will be liable.
A similar halakha was taught by a tanna regarding someone who threw a ball that bounced off the wall and killed someone. Given the fact that people who play ball are knowledgeable in how it will ricochet, such a throw will be considered the direct responsibility of the one who threw it.
During the time of the Talmud there were a variety of different games that were played with balls. From the description in the Gemara it appears that we are talking about a game where a very heavy ball was thrown against a wall, and the ball had to bounce back at a certain angle and distance.