"One of the big advantages is her height and the power she can transfer. Right from the beginning, she had great feel and body awareness, and that great high jumper's take off.
"I've had heaps of athletes who had the talent but she can train really hard and follow a programme. She is the full package, physically and mentally.
"She has that rare gift of being able to channel all that adrenaline and focus. The weekend was a good example, where it came down to one last jump and she was able to nail it when it mattered."
McCartney had handy genes for pole vaulting. Her mum Donna Marshall, a GP, was a gymnast. Her dad, William McCartney, a lawyer, was a high jumper.
"I remember the first time I bent a pole and it was a weird feeling," McCartney says. "There is nothing quite like it. I felt a bit out of control but I really enjoyed it and kept going.
"From the beginning, Jeremy has taught me the right techniques. I am also very competitive, but I suppose all sportspeople tell you that.
"I work very hard. I put a lot into my academic side and get good grades. I've always been independent, happy to do my own thing."
McCartney is currently working through her routines towards the top-drawer 16-stride run up - the junior world record of 4.64m came off her first competition of the season using a 12-stride approach.
Whereas Rio was once a stepping stone, expectations have been raised. She has competed in three international junior/university events, and will fast-track her experience by training with two-time Commonwealth Games pole vault champion Alana Boyd in Australia and then competing in Europe next year.
In this case, behind a groundbreaking world-class athlete, is a coach with an indomitable, pioneering spirit.
McColl, 33, was a gymnast who took up pole vaulting in his 20s and won a couple of national titles. But New Zealand is virgin pole vault territory, so McColl uses the internet to study hard, make contacts - such as renowned Australian coach Steve Rippon - and swap videos and ideas with the leaders in this spectacular field event. McColl's mentors include an Estonian combined events coach Katrin Klaup, who is the mother of his fiancee, heptathlete Mari Klaup.
His quest to put pole vault on the map here has been an expensive and exhausting business. Faced with a pile of old and potentially dangerous poles, he began importing the latest models from the US. McCartney alone uses about 30 carbon fibre poles of various stiffness, many suited just to her.
McColl has amassed about 160 poles for his squad. Full price for each ranges from $600 to $1200, and the shipping charge is $1200 a load. A deal with Gill Athletics helps, but his wallet has taken a hammering. Until becoming a fulltime coach two years ago, his six-days-a-week job as a builder provided the finance.
"I've funded it out of my own pocket, pretty much," McColl says. "I don't even want to think about the cost or try to check it. It's a lot. It was very tough when I was coaching and building. I hit a few lows."
Bit by bit he chases his dream, and is now on the national coach accelerator programme.
"The sport is so intriguing," McColl says. "I love the way you can take an athlete and teach them. It's like putting a puzzle together. It's an event with so many events within it.
"I've always believed New Zealand can become world-class because of the way Kiwi kids are talent-wise. They are very keen on extreme sports ... and you don't have to be the most amazing athlete to be a pole vaulter. What you need is a lot of skills."
McCartney appreciates the extremes to which McColl has gone as she sets about pursuing her dream. "New Zealand doesn't have a pole vault background and I'm grateful to him ... I'd be nowhere otherwise."
