So Rennie was a part-Rarotongan troubadour with a few killer punch lines. But could he play?
The man who now rules the roost over professional rugby in this country is quick to note that Rennie's value went way beyond clubroom versions of Brown-Eyed Girl.
Rennie enjoyed a 59-game career for the union during one of the golden ages of New Zealand rugby, from 1986 to 1991.
"He was a big strong runner of the ball," Sorensen said. "He was the first of the big crash tacklers at inside centre. He tackled like Sammy Tuitupou - he was an up-in-your-face type tackler."
Sorensen recalled his legs, particularly his calves, being massive balls of muscle, yet belying the image of a one-dimensional crash-man, Rennie rarely tucked, preferring to carry the ball out in front of him to confuse defences.
"He was critical to that Wellington team. He played alongside John Schuster and we had guys like John Gallagher at the back. It was a pretty lethal backline in those days."
Undoubtedly, however, Rennie's route through the coaching ranks has proven a lot more circuitous than it was through opposition backlines.
A schoolteacher at Fergusson Intermediate in the Hutt, Rennie coached every sports team the school produced.
"Being a school teacher helps," Sorensen said. "The fact teachers have to stand up in front of a classroom and deliver 10 speeches a day makes them very good at communicating to audiences. They're very good planners. They have their whole week planned out in blocks so they lend themselves to being coaches."
All four of the Chiefs' coaching staff - Rennie, Wayne Smith, Tom Coventry and Andrew Strawbridge - have teaching backgrounds, giving credence to that belief.
Rennie started coaching juniors, under-21s, then the Upper Hutt seniors. His coaching career was on the move as his teaching career came to a halt.
Rennie bought a bar and dedicated his working life to making The Lonely Goatherd the place to be seen in Upper Hutt. Having said that, competition wasn't thick on the ground.
"It was the only significant 'other' pub in Upper Hutt that wasn't the Cossie Club," recalled Sorensen. "But it was fantastic."
Rennie's coaching quickly advanced from Upper Hutt, to Wellington B, to the NPC side, to a role as Graham Mourie's assistant with the Hurricanes.
Rennie was unlucky not to prise the Ranfurly Shield off Canterbury, a win that might have sealed a long and fruitful tenure in the capital. It wasn't to be. The Hurricanes did not go so well in'02, with just three South African teams propping them up on the table.
Mourie walked and Rennie went out the same door, back to the Upper Hutt under-21s.
A life of coaching obscurity seemed destined to follow until Manawatu came calling in 2006.
Three world championships with the NZ under-20s confirmed he had a gift for coaching age-group teams, but it was Rennie's work with the strangely monikered Turbos that caught the eye.
The once-proud Manawatu had become the sort of province that could raise four Whitelock boys within their borders and not have a hope of retaining their services.
Rennie took a group of committed but thinly talented players and worked them to the bone. Winning consistently might have taken time, but they started playing in a style that took the game to their more vaunted opponents.
It was a frenetic, high-energy game, one that will perhaps be harder to replicate successfully at Super 15 level.
They'll have fun trying though.
"I've never been coached by Rens, but the thing that keeps coming through our players is that they love playing for him," said Sorensen. "He can be quite a hard taskmaster, but they find it easy to accept from him."
