We also ran into problems with balls bouncing out of the high goal, and for us it always happened the same way.
If we lined up just to the right of the center goal (the same thing would probably happen from the the left of the goal), the ball would hit the back corner and bounce out the right goal. I believed this happened three times in Boston, and it caused us to lose our first quarterfinal match when it bounced out during auto.
This video shows what happened.