I agree with the others have said. A 4-7-9 on a hit that looks mostly flush means the ball was charging too hard and/or finishing at too steep an angle. It's basically a fast 8 that also leaves the 9-pin. If you would've watched the ball leave the pin deck, my guess is that you would've seen it moving way left, probably exiting the lane through the 8-pin slot. We see these and "pocket" 7-9's at my center all of the time due to really snappy backends. These aren't very much fun because you think you've thrown a pretty good shot only to be left with a likely open. Sadly, it's just part of the modern game because the combination of bowling balls and oil patterns allows for nasty-strong angles.
