Firstly, Dugan is gone no point looking back to the past and what might have happened. He was offered a contract and decided against it. End of story.
As far as Dufty is concerned there are 2 points that need "coaching".
1. Bombs: arent easy to take at the best of times, Slater for example has dropped plenty in his time at fullback. The issue with Dufty, IMO, is he is more concerned about getting smashed after taking it. Hence he lets it bounce to take that situation out. If I were coach, I would send him to a week or 2 with the Sydney Swans just to get an idea of how to take bombs, attacking the ball and how to protect yourself.
2. Sweep plays: always are McInnes to Hunt/Widdop then the Dufty. This worked for a while but easily coached against. Like to see him through the middle more but seems hesitant to join in through the tougher stuff.
He is 20 or so games into his career under McGregor, no development, no variation in him play. A decent coach woyld have been drooling at the prospect of taking him to an elite level.