The angry father appeared at his shoulder as he packed up the team gear bag.
"Just what do you think you're doing, leaving Jason on the bench for most of the final? It's bloody ridiculous! You don't know your job. Just what kind of a coach are you anyway?"
The coach thought, "I've been successfully coaching happy teams for 25 years. I've given up hours of my lunchtimes and evenings and weeks of my holidays for other people's kids because I love to see them have fun, learn a skill, and grow in confidence as part of a team."
He realised he had not seen this father at any of the weekly games, but he didn't say any of this. "Thanks for your input," he said, trying to remove the irony from his tone. "Sorry I can't stay and chat. I have to referee the next game."
Turning his back on Jason's irate father, he walked away to get the under-16 girls' game started.
This recent incident was related to me by a teacher-coach of my acquaintance. It goes some way to explain why many teachers are walking away from coaching roles.
The toxic attitude of a small but growing number of parents, and their lack of manners, result in exchanges like these.
Combine this with an ego-driven, one-eyed view of a child's abilities and the result is a strong disincentive to any teacher's coaching ambitions.
Of course, there are still many wonderfully supportive and grateful parents who turn up to every game and help out whenever they can. These are the people who can be seen at the end of tournaments picking up rubbish, sweeping floors and stacking gear.
They are the folk who organise food supplies for the week-long trip to a tournament and drive a vanload of kids there and back. And they often organise a much appreciated thank-you card and a box of chocolates or bottle of wine for the coach at the end of the season.
Unfortunately, a couple of incidents with angry, unreasonable parents is often enough to make a coach think twice about carrying on next season, no matter how good the rest of his charges' parents are.
The damage potential of toxic parents is not limited to the coach either. Talking to the cook and driver of a team competing in the recent Secondary Schools' Basketball Nationals, I wondered how she could carry on. Her son was the team coach and, with no one to act as manager, he had roped in his mum, a veteran of many tournament trips when her sons were playing.
Because of work commitments, she had arrived at September's regional qualifying tournament a day late. The team was playing game two in their well-worn second uniform strip, because there was no-one there to launder the first strip after the first day's games.
She was set upon moments after she arrived by a parent complaining about the team's shabby turnout. "I asked him if he'd like to do the laundry," she told me, "and he replied, ‘No way, I'm on holiday'!"
Parents of this team's players had come to Nelson to support the team at the nationals, but they hadn't responded to invitations to help prepare breakfast before early games.
"I guess they're on holiday here too," she remarked.
It's this kind of graceless behaviour that leaches the goodwill out of coaches, managers and helpers.
The toxic parent problem occurs at all levels of sport. In his last year at college, our youngest son was selected in a New Zealand Secondary Schools basketball squad of 12 to play a series against Australia.
Husband Steve and I went north for the games, held in Hamilton, Tauranga and the North Shore. In the first two games, the New Zealand coach played all his players and Australia won both games.
In the final game, the coach decided to use the eight players he judged were a combination that could beat the Australian team. He was right and New Zealand won the final game - quite possibly the first time a New Zealand age-group team has ever beaten the Australian equivalent.
It was an amazing achievement in which the four squad members who didn't get on court played a vital role as encouragers and supporters from the bench.
Amidst the applause and excitement as the final whistle blew, Steve and I were astounded to see two mothers of the bench players march over to the New Zealand coach, bail him up behind the sub-bench and deliver several earfuls of abuse for not playing their sons.
In an embarrassingly public incident, officials had to physically separate the angry pair from the coach. Not surprisingly, their red-faced sons disappeared as soon as the fracas began.
While toxic parents are unpleasant for coaches to deal with, it's the children who are the real losers.
A coach can walk away and decide to put time into something more rewarding, such as his or her family, for example, but the children he or she coaches and those who would have been coached in the future will miss out.
And we're all the losers when that happens.