Stainless, Bushed PRW Rocker Arms

No, the roller rolls across the tip. If it skidded, every roller, no matter what brand, would soon develop a flat spot.

The cause of the worn bush seems obvious to me: poor/soft bronze. This particular valve train is lightly loaded, yet it still wore the bronze. I wouldn't be using grooved shafts either, you just remove surface area in a critically loaded area. One of the benefits of bronze is it requires minimal lubrication. Since two methods of oil supply were used, both normally very reliable, it is hard to believe the failure occurred through of lack of oil.