For Parker it was a chance to learn from a coach who had already taken a Kiwi to a world heavyweight title fight; while for Barry it was, in a way, a shot at redemption.
Whichever slant you take on his acrimonious split with David Tua more than a decade ago, which dragged on through the courts for six years, it was a sad way for one of New Zealand sport's most enduring partnerships to end.
Barry and Tua have not spoken since they fell out in 2003 and although there is a book about the split, Barry has not read it and has done his best to move on from it.
The saga, which was complicated and included Tua's former co-manager Martin Pugh, left Barry disillusioned with boxing.
He had to be coaxed back in to the professional game in late 2009 when he guided Beibut Shumenov to a light heavyweight world title.
Shumenov defended the belt three times under Barry before they parted ways and Barry began working as the director of wellness for Union Gaming Group after he took six months out to have ankle surgery.
"It was a great life. But there was no challenge there for me. There was nothing to make me hungry."
Around Christmas 2012, Duco, Parker's promoters asked Barry to train their heavyweight hope.
Barry had undergone four shoulder procedures to repair a rotator cuff and said he would need as many months on the shelf before he could train someone again.
Given the fallout with Tua and Barry's departure to Las Vegas, many people remained divided on what to make of the former Olympic medallist but he was the man to whom Duco wanted to entrust their prized asset.
Says Duco's Dean Lonergan: "I've known Kevin for 20-plus years. So I was always adamant he was the right guy for the job."
Duco wanted someone who understood Kiwi culture and was based in Las Vegas given it is the mecca of boxing.
It was an ideal set-up in theory but it had to work in practice.
"With a coach and a boxer, you've got to have a strong relationship," Parker says. "We get along well, we have good laughs every day and training's fun."
As for the history, it didn't bother Parker.
"For me, it was about improving my boxing. I didn't know who Kevin was and I didn't want to ponder on his past or think about it.
"They dealt with it, not me. All I had in mind was to get a good relationship with the coach so we could work well together."
As we know now, after cruising to a points decision over fellow Kiwi Brice Ritani-Coe in California in May, Parker knocked out Botha in the second round in Auckland.
It was evidence that this could be the beginning of something worth watching. After the bout, Parker's promoters wanted to lock Barry in to a long-term deal but he didn't want the commitment and preferred to just let the relationship grow.
"I went, 'Let's just leave things as they are.' So we don't even have a contract, that's how I'm working."
Isn't that a risk given boxing's dark side, Kevin?
"I believe in what I do. My results speak for themselves."
While you could say this is a carbon copy of Barry taking another Kiwi-Samoan fighter in search of the world heavyweight title, the 54-year-old doesn't see it that way.
"I'm a much different person in 2014 than I was in 1992," Barry says. "I'm a much smarter man in boxing, my experiences have been far greater than in those days."
Parker's latest bout against Brazilian Marcelo Luiz Nascimento, which was due to get under way in Germany this morning, marked the fourth fight the pair have worked together.
After countless hours in a gym, holding pads and sharing tactical knowledge with his fighters, Barry's excitement is still there.
There's a buzz when the lights go on, the music starts and Barry begins his walk to the ring with his student. "There ain't nothing better," he beams. "That's what keeps me young."
Daniel Richardson is in Germany courtesy of Duco Events.
