"A Bob Dwyer phrase still rings in my head today. He said: 'The best coaches in the world are the best players.' He meant that, if you want to become a better coach, learn from the best players. Every time I talk to a leading player, I learn more from them than they learn from me."
Indeed, Jones goes on to write that Barrett was an open book when it came to sharing his rugby knowledge and hinted that the England side were better off for his experience.
"In England there has been much criticism of me coaching Suntory, and working with Beauden. But for me the best thing is that Beauden, one of the world's great rugby players, is comfortable enough in himself, as I am in myself, to talk about the game so openly.
"We're not trying to take anything away from each other. We're trying to help each other and to just share our love of the game. Winning matters hugely, but I want the game of rugby to grow and to be truly great."
One of the traits Jones found most inspiring about Barrett was his work ethic during a stint perceived as a cushy money-grab by plenty of rugby pundits.
"When working with Beauden, I have learnt more about his humility and the way he keeps working at his game. He has twice been the World Rugby's Player of the Year but, with Suntory, which is supposedly meant to be an easy gig for him, he comes out every morning for training with the vim and enthusiasm of an 18-year-old.
"One week, even when there was no game on the weekend and he had a crooked neck and had to wear a medical bib, Beauden was at it with so much purpose and intent. He loves practising and training and playing, and I savour that undying passion that surges through him.
"I've spoken about Beauden to my players in England. Over here, considering the length of the season and the environment, some players tend to go through the motions in training. But you need to find a way to retain that boyish love and enthusiasm for the game."
Indeed, that attitude did wonders for Barrett and Suntory as he guided the side to an unbeaten regular season record and a place in the Top League final in which they were finally defeated by Robbie Deans' Wild Knights.
Meanwhile, Jones returned to England following his time with Barrett and led his side to three straight home victories - including wins over Australia and South Africa - that quickly silenced his critics.