Thanks for the comments.

The shot was not designed to be a spectacular break, more of a medium strength hit on a clump of balls. It would be way too easy to have the cue ball smash into the pack, and have all the balls fly off frame at lightning speed. The whole aim was to keep as many of the balls in the shot as possible throughout the entire animation, while maintaining a realistic look. Try it yourself on a real table. If you shoot a cue ball lightly at a pack of balls, the only ones that really move are the outer edge balls.