However, his awareness and handling skills make him a good fit for the No14 jersey and he is building an excellent combination with fullback Melani Nanai as the Blues show signs of improvement under Umaga.
"It has definitely been a challenging season, but nothing that I didn't expect," he said. "I didn't necessarily think I'd be able to waltz on in here and start for a Super Rugby side like the Blues. I knew there were going to be hard times. Pre-season is a whole different beast and I had it in perspective, I guess It's nice to be playing consistently."
A former 200m and 400m runner as a schoolboy, Duffie played AFL and volleyball as a youngster, two sports which helped him hone his skills in the air.
"I guess it was a point of difference I had in rugby league and it probably gave me a foot in when I first started [in Super Rugby].
"I'm not a winger that's going to run through guys like a Julian Savea or a Nemani Nadolo, so I have to have something different. It's something I learned in high school, playing AFL in Auckland, and I really loved my volleyball growing up so that was another thing [which helped]."
Duffie, part of a backline which has gone to a new level since the June international break, with Nanai, Ihaia West, Piers Francis, Male Sa'u and Tevita Li all playing with a new confidence and purpose, has signed for North Harbour for the next two seasons and has another year on his Blues contract.
His next rugby assignment is against the Waratahs at Eden Park on Friday, a probable match-up with Israel Folau, one of the best exponents under the high ball in any code. It is a testament to Duffie's form that the home side will be favoured to beat a Tahs team whose playoffs hopes are hanging by a thread.