it doesn tell you much really.
but what would, is to break take cue ball in hand or not, and just count the balls you make before you miss. after enough tries you will get a perfect idea of how many balls in rotation you can run most times.
then from that you can now find out your best way to actually play nine ball.
the vast majority will find out that trying solely to run out after the break is not the best path to winning the game most times.