All you need is a little longer oil, whether it is applied or buffed, and most bowlers will stay where they are used to being, throwing marshmallows into the pocket, flirting with 8-10's and 7-9's. Even though it looks flush if the ball isn't done sliding the danger exists.
Back a long time ago, when rubber balls were the weapon of choice, it was nothing to see a dozen or more weak pocket splits every night you bowled if there was just a little more oil on the lanes than normal. A poor release, ball slides into the full pocket, bingo. Even on some fairly good releases you still flirted with those weak pocket hits because the ball didn't give you anything for nothing like today's hook in the box miracle balls. A little too flat into the hole and the ball bounced off like the pins had armor plate.
Next time you see this happen watch real close as the ball hits the headpin. If it is still skidding it will bounce and the pin carry will be poor.
