I'm not a big fan of Gordon's game, even if you ignore his health concerns.
He's not a good passer, has trouble taking care of the ball, and manages to have a below average TS% despite being a slightly above average 3P shooter.
His only real skill is three-point shooting, but he isn't even elite at that, just okay. He is decent at drawing fouls, too, but not at a rate to get excited about. Besides that, he hasn't yet shown he can manage even average production at every other facet of the game.
He would be a minor upgrade over Avery Bradley on offense. And, honestly, I think Avery's defense is fairly overrated anyway. So ... I wouldn't mind getting him, because he has SOME potential being so young ... but I wouldn't give up #17 for him. As long as we are dealing with potential, might as well go the whole way and not pick a player that has been mediocre at the professional level already.