Sounds like me, but I have a book average of about 192 and I'm not a sandbagger. I actually bowl better at a tournament at our house, since they always lay fresh oil on the lanes. I usually bowl better when the oil is fresh. Our house lets people bowl on the lanes that have been freshly oiled before the leagues. So when we get to them, their kind of screwed up. I have a hard time adjusting to these conditions and will average around my book average. Put fresh oil and my average increases.
Have you looked the Bowl.com to see if he has ever had a high average?
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