Doug,
I'm gathering from your post that the ball weights are the same, as are static weights after drilling. I looked up the ball stats and they're the same,so that should eliminate any difference in weight block action.
The only difference is coverstock as I see it. Maybe he's throwing it different,but then again you threw it and it did the same for you.
Did you drill it??? If so then that eliminates a mismarked Cg that could cause a ball reaction that is actually off from what he wanted vs. what the mismarked Cg could have led you to believe you were drilling for.
The only thing that comes to mind is that one of the flip blocks---maybe I have the wrong terminology here-----may be improperly positioned and therefore causing tracking over the holes.
I know that you're much more knowledgeable about drilling than me,but Iv'e learned from hanging around pro shops--especially The Author's---so I hope this helps.
I'd appreciate a message when you do figure this out so that I can learn from this experience,too. Thanks Doug
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Chris
Lane#1--nothing else hits like 'em.