Hardie is no soldier of fortune
John Hardie's naming in the 31-man squad just a month after the New Zealand-born flank set foot in Scotland raised the hackles of many former players who felt it was a disgrace that stalwarts such as John Barclay had missed out.
Cotter dismissed the complaints and his unsentimental approach to the selection has paid off.
Hardie has been outstanding both in the win over Japan and then, after missing two games with a head injury, against Samoa which booked a quarterfinal against Australia on Sunday.
The 27-year-old – who scored a try in both matches – is adamant he is not an opportunist seeking to play Test rugby because he is not good enough for the All Blacks.
He has a blood right to wear the blue jersey thanks to his grandmother Christina Lumsden, who was born in Culross in Fife.
"She left Scotland in 1925 and settled in Edendale in the Southland region," he told The Guardian newspaper.
"Big Jim Mason [Scotland's broadcast manager] has shown me the document she signed off the ship. Sadly she passed away a few years ago when she was 97, but she had a good innings."
Hardie, who played Super Rugby for The Highlanders, is being followed by his mum Helen and dad Russell, who should be back in New Zealand at the family farm as it is lambing season. His sister is also in England.
Hardie said he would show them the original papers he had unearthed on their heritage.
"We looked up all that sort of stuff and it was really cool to see where she came from," he told the BBC.
"I want to print it out and show my mum and dad because they're over here. They arrived three days before the first game. The Japan game was awesome for them."
Hardie – who was accompanied in the back row against Samoa by Zimbabwe-born David Denton and England-born Ryan Wilson – admits he took an enormous gamble giving up his contract with the Highlanders but he needed a new challenge.
"I came over [to Scotland] and people said it was a big risk," he told the BBC.
"But I didn't think it was a risk, I thought it was an opportunity. I knew it was going to be tough and I knew I had to work really hard to prove myself. I was out of my comfort zone.
"I'd been with the Highlanders for seven years and I was in my comfort zone.
"Coming over to Scotland really brought the best out of me as a person and I think it's helped my rugby as well."
It could be said that it has been beneficial to both countries as Hardie's new found fame abroad has helped the New Zealand farming village of Dipton, notably its school with just 60 pupils.
The head teacher Richie Crean needed an extra teacher and hit upon the idea of raising money to pay the new recruit with a social media question and answer session with Hardie, at the Scots training base, conducted during a fund raiser dinner.
It was a success on both a public relations and financial front. Now, aside from the All Blacks, there is only one other team the inhabitants would like to win the Webb Ellis Trophy on October 31.
"Scotland would be the number two team as far as Dipton is concerned," Crean told the BBC. "Everybody is following John at the World Cup."
Agence France-Presse