Just wanna clear some stuff up-
The Hype core is nothing like the SD73 core- just look at the RG and DIFF numbers. Its more like the core that was in the Illusions than the core that was in the SD73 (even then....).
The Natural and the Grenade are true urethane covers. I can't speak for the other guys, but this is the case with these two.
I can say with 100% certainty that the Natural was not a sales flop. I was one of the staff members that was complaining about needing a urethane for the better part of 2 years prior to the Natural's release and was told that it probably wouldn't sell because the average bowler just wants more and more hook- but within weeks it was acknowledged to me that sales were better than expected, so the ball sold. If it didn't, why would the same company bother to bring out ANOTHER nitchy type ball in the Grenade? They wouldn't, because they aren't in the business of pleasing guys like me, they're in the business of selling bowling balls.
The urethane resurgance is also partially a biproduct in the expansion of sport leagues. The more of those you see, the larger variety of product will sell in your area. I'm not gonna pretend to sell several urethanes a week out of my shop or anything, but we definitely sell enough of them to justify having the product on the market.
