Guys,
My belief:
The problem is that pearl urethane will still grab the lane earlier than polished, mild resins, when the heads start to dry up or there's really short oil. This is true Unless you have higher balls speeds or 90 degrees rotational axis or some combination thereof.
When you move deeper, inside the 4th arrow, SOLELY because there's not enough oil, a mild pearlized resin, with enough backend (important factor) seems to work best. If you can stay at the 3rd arrow or outside it, at the arrows, and still get proper length on a ball like the Slate Blue, it will give you what you need. The majpr factor in this scenario is having enough energy left in the ball, after it starts hooking, for it to carry decently.
Pearlized urethane's forte is control and weaker backend after it starts to go thru the skid/hook/roll cycle.
I tried my SBG 3 weeks ago and couldn't get it long enough to retain energy. Once I had to go inside the 4th arrow, I couldn't get enough length on it, or have enough left to make that huge turn to the pocket. Had to go to polished resin, with a laydown point at the 39 board. OUCH! Thankfully they have put down serious oil since that time.
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"We get old too fast, and too late, smart."