"It was always planned to have the operation when I did. I dislocated it in the Blues-Chiefs Under 18 game in July, but I was just on a faster recovery programme," says the articulate Plummer.
"The first time I did my left shoulder (2015) it was in more of an awkward position. The second time was unlucky. I had a brace on and I was strapped up," he says.
"I love tackling and I love people trying to challenge me in that first channel, but it's often the angles and positions you find yourself in."
It helps that he has played a lot of rugby at second five, where he had to slot in at late notice for NZ Schools against Fiji Schools, when nominated No 10 Paul Roache was injured in the warm-up. Not only was that a hard team to make, but there were a plethora of goalkicking options. Plummer won the nod and did the job.
His First XV career started in Year 11, in 2014, where he was used all over the backline, on the wing, at fullback and at No 12. Dion Fraser, a Fiji Under 20 rep, was the incumbent first five and Plummer had to bide his time. Jordan Trainor, another sharpshooter off the tee, was the gun at fullback.
Plummer first shot to wider TV prominence with a fine display in the epic semifinal between St Peter's and Auckland Grammar that season. He finished a superb team try on the left wing and then set up Trainor with a nice break. St Peter's narrowly lost that day against their Mountain Road neighbours, but they have tended to punch above their weight in recent seasons under the guidance of coach Mark Wilson.
This season they again reached the semifinals, Plummer kicking all the points in sweet, tight wins over private schools St Kentigern and King's.
"We hadn't beaten St Kentigern in seven years, which is pretty unreal, and yet we hadn't lost to King's in three years. You don't take that kind of stuff in until the end of the season," he says. "St Peter's this year prided themselves on defence. That's why we did so well."
Plummer himself performed admirably, scoring well over 100 points, even though he missed some games with his shoulder injury. His solid technique and mechanical style serve him well off the tee and was in clear evidence with seven from seven against Australian Schools, plus a smartly taken drop goal. It should have been enough for the Bronze Boot award for the home side, but he was a touch unlucky to miss that honour.
Not 15 metres from where we are chatting are erected a set of goalposts. They are not quite as big as those at Dan Carter's parents' place in Southbridge, but they are a useful tool for working on technique. They have been up for almost a decade, since he was a junior at the Karaka club, and give a sense that goalkicking has always been a key plank in Plummer's game.
"I've always wanted to be a goalkicker, just because of how much fun it looks, but it was really only 2015 that I started getting into it properly," he says.
Plummer enjoys the responsibility of winning a game for his game, and has improved his mindset if he misses or has a bad kick. Now he is better able to block out the distractions and make it just about him, the ball and the posts. All good goalkickers thrive on that feeling, the only time in a game of rugby that the eyes of everyone at the ground are on one player.
Plummer will miss St Peter's, though he won't miss the 90-minute car-train commute every day.
"It's been a big year of juggling, but I think that's what your last year at school is all about."
Now, with the help of his rugby scholarship, and with the first-hand knowledge that he cannot put all his eggs in the rugby basket, he will be hooking into his commerce degree, majoring in management and marketing.
"Mum and Dad have drilled into us that sport is all good until you get injured. I've had two years where I've had half a season off, so that's put it into perspective that you need something outside of sport. I've always been pretty motivated to get an education outside of sport, so I'm looking forward to the ride."
He is the second recipient of the Royal Wolf Tertiary Rugby Scholarship. Former Liston College flanker Adrian Choat, now with the Waitemata club and an Auckland Under 19 rep, was the inaugural winner in 2015, and has done well with both his studies and rugby this season. Choat, who is doing an engineering degree, sends out regular detailed and amusing updates to stakeholders and supporters.
The scholarship, valued at $10,000 per year for three years, was negotiated with Royal Wolf, New Zealand's leading shipping container firm, by the Auckland Rugby Union Supporters' Club Junior Rugby Foundation. It is awarded annually to Auckland secondary school leavers to commit to the Auckland union.
Plummer, who also holds an ARU academy contract, has chosen a top club for 2017. Grammar TEC were the 2015 Gallaher Shield winners and 2016 runners-up. The plan is to be playing premiers, where he will be outside a choice of two fine halfbacks in Jono Hickey and Lisati Milo-Harris, the latter another St Peter's old boy rehabbing from long-term shoulder issues. Outside him may be St Peter's midfielder AJ Lam, a cousin of Michigan Lam (son of Pat), who has played a lot of rugby at No 10 for the club. Plummer himself has received goalkicking tuition from Simon Hickey, the 2015-16 Auckland skipper out of the Grammar TEC club.
So we turn to goals for 2017, other than making his mark in premier rugby.
"The Auckland Under 19s is a really good opportunity first year out of school and then NZ Under 20s in 2018 is an ongoing goal," he declares.
When it is put to him that, all going well with his physical return to the game, a place in the 2017 Auckland Mitre 10 Cup squad is not beyond the realms of possibility, especially as there is no clear heir apparent to Simon Hickey, now plying his trade in France, Plummer is reluctant to get far ahead of himself. Form and fitness will dictate that, and he is right.
This Saturday, Plummer will be at Eden Park, where the College Sport Young Sportsperson of the Year awards are being held. He is a finalist in the boys' rugby category, alongside the talented MAGS duo of Caleb Clarke and Waimana Reidlinger-Kapa.
He has a good show of taking the gong. And he has a good show of doing well in whatever he puts his mind to in life.
