"He's been marvellous and has fit in seamlessly, really."
Nonu was part of New Zealand's successful World Cup campaigns in 2011 and 2015. With more than 100 matches for the All Blacks, his experience on the world stage could also work in his favour in his bid to get back in the black jersey.
Many Kiwi fans will fondly remember his stunning solo try in the 2015 World Cup final.
If selected for the 2019 tournament, he would have the opportunity to become one of the first players to win three World Cups, along with potentially Sam Whitelock, Kieran Read and Sonny Bill Williams.
With his addition, the Blues may boast one of Super Rugby's most exciting midfield combinations as Nonu lines up alongside crowd favourite Williams.
The attacking prowess of these two could create plenty of headaches for opposing defences, an area where the Blues struggled last year.
And despite Nonu being away from the New Zealand game for a few years, Coventry said he hadn't missed a beat and had returned with plenty of motivation.
"Ma'a is in great nick," Coventry said. "He's a true pro. He's come back into our environment, he brings all that experience. Just watching him train, he and Sonny have fit into our team beautifully."