NN was awful as the season went on last year but If he can bounce back to his rookie season, he's someone you want to keep around. He could be the perfect 7th dman behind KK, someone you can unleash when trailing or train him to become a PP specialist. When he's on, he possesses a pretty unique skillset. Only 80 NHL games played so far, it's not too late.
Yeah, Nesterov has more upside than a guy like Sustr, and experience should work out some of his flaws. I'd put him pretty even with Carle right now, but I'd rather give Nes the experience than let Carle bumble around for another year.