I'd look at this way since I am 61. If he is using the same ball for 33 years diz is correct it would be rubber or poly. Take your way back machine to 1977 and those type of lane conditions of low volume on lacquer/wood. Non-flaring equipment one measured their skill level by the small track they put on a ball. Since, it was low volume not much oil would show up on a ball. Many were still using conventional grip then...maybe your friend still is? Conventional grip, low revs not much oil allowed bowlers to play the track easier. Fast forward to 2010.....OMG you can see where the old duffer is coming from and he still shot 590 probably by adjustments. Possibly the THS has a dry-dry area out to the right or left?
Old minds are hard to change at times.
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Scott