That's a very good question. I know sometimes they specify x number of balls have to pass the side pocket. This has always been kind of a sticky, ambiguous rule.
I will say that I didn't much care for the break when Ronnie did it to win the World Pool Championship. I think it made watching the game a little boring when he would have roughly the same layout every time. I also saw a match with Busty vs. Alex which was likewise boring because Busty did the same soft break and had the same layout every time.
However, I can also see that you'll never really be able to please everyone. From my standpoint as a spectator, it made the game unenjoyable to watch. Keep in mind I fully understand that other spectators can appreciate honing the skill to give yourself roughly the same layout every time that allows a player to give himself the best chance to win.
That leads to my next point...that from a players' standpoint, they probably feel that if it's something that they've worked on, not lucked into, and it gives them a greater chance to succeed, why should it be against the rules, and why should they have to give it up? It'd be very difficult to argue against a guy for taking that viewpoint.
It's a slippery slope to be sure, this soft breaking stuff. I don't care for it, but I can't really find a totally justifiable reason that it should be disallowed, especially if the guy is making a ball or balls.
