A similar D would be a young guy with some issues, though. That's what Athanasiou is. He has a lot of upside, sure, but he's got issues that are going to turn teams off. If a guy like Trouba had refused to sign entirely and sat on the sidelines or something for a few months...that sort of guy. We're not going to get a guy with top3D upside who doesn't have issues and who isn't 35, though. And while we'd probably have a hard time replacing Athanasiou's production with a second rounder, other teams are looking at Athanasiou and wondering if they'll get a guy who'll even show up half the time.
I agree with your assessment of him as a player but I think the valuation of him by other teams, even if you're right in how they'd do it, is silly.
Even with all his attitude problems, he is a remarkably productive player relative to the rest of the league. You don't even have to go to P/60 to see it. Just pure PPG he's a very productive player. He was last season too, without much PP time. And whether or not it was driven by his work ethic, coaching, a lack of trust, whatever, his IT was 15.18 per game for 9th most out of out of 13 regular forwards.
Good production with limited minutes, young, decent size, insane speed, good upside. That's already what you know you're getting for sure. GMs who shy away because of his attitude are either afraid he's locker room poison, which I think is hilarious, or they want to bank on his upside which absolutely won't be reached unless he has a good attitude. But if he reaches his upside he's a star so stop being so scared. Even if his attitude problems persist, he's a very good player already.
By the way, were you saying that Trouba + attitude issues = fair return for a guy like AA? Because damn.