I could isolate 16 made threes for DeRozan from last year's game log and say he went 16-26 on those for 62%.
Or I could say he made 17 of his last 51 threes (more attempts and makes than Rip) for 33%.
Sample size is a bit too small. I think it's more realistic to look at Rip's percentages for his first 5 years, and see that he shot a little under 30% so he was by no means a good three point shooter. And DeMar becoming a good three point shooter wasn't the point of this thread, I was just saying that it's clearly a possibility.
The main point was to compare Rip, a player who was very useful on a championship caliber team, using up the same % of the team's cap as DeMar, to DD.