I never got the impression that Melo was disinterested. Actually as the backbone of the zone, I thought he was very engaged, keeping his head on a swivel, his hands up and seeing the action unfold well. Just based on how much he improved from his freshman season when he was a huge, out of shape disappointment, you can gleam positive things about his work ethic. He lost a good 25 pounds or so and was much better at the free throw line.
The most surprising thing about him is how competent of a passer he is. I think his basketball IQ is very solid.
As for Draymond Green, I think he's very unlikely in the three first. Ainge goes for his type, the highly productive, player of the year winners who lack prototypical size and athleticism in the second round.