I really like Nick Young.
I think he and Rondo would be great together in the backcourt.
I don't like how little he gives other than scoring ability.
I think he could become neutral on defense.
Man-to-man defense is much improved from his early years. Team defense is really poor but playing on a high quality defensively orientated team could help him grow. I like his chances of becoming an average defender after some time in a good environment.
Quality scoring punch + average defense ... with negative contributions via very poor passing and rebounding.