Stu -- I tried very carefully last year to estimate the width of the break box as best I could from the stream. It appeared to me to be about a foot wide, not 9". I think if you will review some of the matches on YouTube you will see that. For example, look at the overhead view of the table at the 5:00 mark of this match:
http://www.youtube.com/watch?v=5SXTQyPEqLs. You can see the breaking marks on the headstring at the edge of the breaking box. Or look at Shane's break at 5:43. The ball is about a half a diamond from center table.
So I'd call that about a foot wide. And I think even at that width that it had some unfortunate results. Excluding Shane from the calculation, the breaker in the 2013 Mosconi Cup made a ball without fouling, i.e., stayed at the table, on only
29% of the breaks. Including Shane, it was 33%. What's your opinion of that -- good or bad that the breaker stays at the table only one-third of the time? Also, break-and-run games almost disappeared. Not counting 9-balls made on the break, only 5% of the games were run out from the break. The break in that Cup actually became just a search for how to make the 2-ball bound off the foot rail and kick the 9-ball into a side pocket or a head pocket. Do you consider those breaking results desirable for the U.S. Open going forward?
So when we hear about a 9" break box, my hope is that it means 9" to either side of center, not 4½" to either side (which, as I said, would be even smaller than at the Mosconi Cup).