I agree with Deadbait on this one. Each bowler has their own tendencies and styles that help to dictate what a "benchmark" ball will do for them specifically. That being said, what I look for in a benchmark ball is something that will give me an honest look at what is out there for a volume of oil, and also when and where the breakpoint is coming out of that oil. If I have a ball that over or under reacts to the oil line, or a ball that never reads the breakpoint correctly, then it will not be my benchmark ball.
My benchmark ball is something I can pull out to find a line on the lane, and be able to adjust where and how I attack a pattern based on the read from that ball. For me, that ball is my Fury, 1000 abralon, no polish.
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MainePBA
"Power tends to corrupt absolute power corrupts absolutely." Lord Acton