By his own admission he has played in every position, yet, until midway through 2012 at least, he had not stamped his name on one he could call his own.
However by season's end – after a courageous, consistent set of performances in defence after the mid-season break – all that had changed and he had found his niche in the defensive 50.
Dunn's form down back was good enough to push him into the top 10 in the club's best and fairest. And earn him a contract extension.
"I think it [playing in defence] suits my natural playing style, being able to use the ball offensively and rebounding out of there is a real strength of mine," Dunn told AFL.com.au before Christmas.
Dunn admits he was initially uncertain when Mark Neeld told him he wanted him to play in defence after the bye. But once he got going he found it hard to imagine being anywhere else.
"I love it down there and I don't want to play anywhere else so it's funny how things change," Dunn said.
Well regarded within the playing group, Dunn admits with a laugh he was heading down the path of being remembered most by outsiders for his moustache and niggling tactics. But there is much more to him as a player, and person, than that caricature.
He will return to Melbourne training on Monday - one of his first appointments facing the club's leaders to explain his part in being evicted from day one of the Boxing Day Test alongside teammates James Frawley and Jeremy Howe.
As well as the occasional bout of white line fever, Dunn concedes his penchant for creativity on the football field has sometimes led to him biting off more than he can chew. But in 2012 he made significant advances in understanding what he needed to do to perform at his best.
"It is funny how much you can learn about yourself in a season," Dunn said.
"I have always thought that I have known about myself as a player but the way I have grown in the last six months as a player, and even off the field … I am comfortable I know my role in the team now."
Dunn makes no apology for his aggressive style, saying he plays a contact sport for a reason. He is competitive and enjoys getting inside the head of opponents if he can. But he is no fool. He has a mature outlook and the balance that comes with fatherhood.
And a confidence about what lies ahead in 2013.
"[It's] just knowing my limits and finding that edge. I'm coming into my ninth season now and in the past I've got caught giving away free kicks or 50-metre penalties and that sort of thing," Dunn said.
"I've really honed in on that and done work with the coaches about where that line is and what it looks like for me."
Now Dunn knows his role and understands that his teammates respect him. He enjoys the camaraderie that comes with being in the backline and appreciate that the coaches have expressed their faith in his ability to perform a role.
With 99 games behind him he is far from done.
"I'm pretty competitive so I love playing on someone, and aiming to beat them," Dunn said.
"I've got a pretty busy mind so playing down back gives me a clear focus."
