It's hard to tell the difference, because in both cases the ball seems to "quit". One way to get a hunch, though is to pay attention to what type of balls are being thrown, and where they're being thrown.
Too many shots with plastic or polyester balls will push oil down the lane faster, especially if it's inside where a higher concentration of oil is to begin with.
Either way, my first move is a small one to the outside, so if it's carrydown the ball with start sooner and hopefully get through it better. If it's rollout, then the ball may rollout even earlier and I will hopefully notice that, too. If you've moved outside and still can't tell, try throwing a shiny pearl reactive ball out there (assuming you're not already) and see it if responds better.
Rollout is caused by too much friction too early on the lane, so by going to a shiny ball you're delaying that friction a little bit, and then the ball will respond faster to that friction and make a more angular move.
I don't have all the answers, but hopefully these ideas will give you a place to start. Good luck.
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Lane Carter, Strike Zone Pro Shops - Salt Lake City, Utah
Brunswick Amateur Staff