Timeframing makes a difference. If you look at just the last 4 years, Duke didn’t start going the one and done route until 2016, it looks much different. Most of the guys they lost went first round.
However, you're list of Duke players has some major issues for this discussion:
You listed Kyle Singler, Demarcus Nelson and Amile Jefferson, they left Duke after 4 years, they exhausted their eligibility, then tried their hand at the draft. I'm not sure why they are on your list, Duke didn’t "lose them to the GL"
Bolden left after his Junior year and let's be honest, he was terrible and had reached his ceiling. I think we can all agree on that.
Had to do some research on Czyz, he shouldn't be on your list either, he played 2 seasons for Duke (08-10), then he transferred to Nevada, where he played 2 more years, so he also exhausted his eligibility. Duke lost him to transfer, not the GL.
I'm not sure why Alex Murphy is on your list, he played at Duke for 2 years, transferred to Florida for 2 years, then played a 5th year at Northeastern. He also exhausted his college eligibility.
I guess maybe you didn't realize this, but we were talking about freshmen and Sophomores that left early for the GL. You got all the UK players correct, but most of the Duke guys you listed played 4 years in college before entering the draft.
Thanks, you helped me prove my point.