The pair go way back.
Walter spent five seasons coaching the Otago Volts before moving north to coach Central Districts.
The South African-born 50-year-old had a two-year stint as the white ball coach for South Africa from 2023 until he resigned in April this year.
He took over as the Black Caps coach from Gary Stead in June.
But it was while he was in Dunedin that he first ran into Duffy.
Duffy was struggling with his action in the summer of 2016-17. In a bid to add some extra pace and press for national honours, he had lost some rhythm in his action.
Walter had just arrived in Dunedin but thought Duffy would benefit from a spell away from the game to work on his bowling in the nets.
It felt like a bold move to sideline one of Otago’s best bowlers or, as the Otago Daily Times described it at the time, to send him to bowling boot camp.
But Duffy has talked about it being the making of him as a bowler.
Walter, however, played down his contribution.
‘‘I don’t think it was quite boot camp,’’ Walter said, chuckling.
‘‘But we have come a long way. I was only a small portion of his journey.
‘‘He played for Otago well before I arrived, and it’s been a number of years since I’ve worked with him.
‘‘It’s certainly always great to see the performances that he’s put in and the success he’s found. Obviously, this is just one series. He’s been very successful over the last two years.
‘‘And the credit goes to him, really, for the work that he’s put in along the way.
‘‘He’s a very coachable cricketer, and it’s nice to work with someone who’s open to information, willing to try stuff, not stubborn and closed off around their own performance, but willing to really get into the nuts and bolts of it.’’
That sums up Duffy. The 31-year-old has rolled up his sleeves and worked hard at his craft.
He was named player of the match for his four for 35 in the fifth T20 against the West Indies in Dunedin on Thursday.
He was also named player of the series. He was the leading wicket-taker with 10 at an average of 12.10.
Earlier in the week, he climbed six places to No 3 on the ICC T20 international bowling rankings.
For a guy stuck in the queue behind Tim Southee and Matt Henry for so long, he has really shone since getting regular game time at the international level.
And while Walter plays down his role, Duffy is clear about who helped him get to where he is today.
He described the period he worked on remodelling his action as ‘‘the best thing I ever did in my career’’.
‘‘Not only did it sort of get me back on track, but it taught me a lot about how I need to function as a bowler,’’ Duffy said.
‘‘I’m excited for everyone else to, you know, discover who [Walter] really is as a person, as a coach, and I think that’s slowly happening now.
‘‘I know the lads are really enjoying him, and, yeah, it’s an exciting thing to come to work.’’
The Black Caps and the West Indies move on to a three-game ODI series, which gets under way at Hagley Oval tomorrow.
While Duffy would seem like a shoo-in for the starting XI, Matt Henry returns from a calf injury and Blair Tickner grabbed eight wickets in two ODIs against England recently.
Kyle Jamieson is also gunning for a start, and all-rounders Nathan Smith and Zak Foulkes add to the excellent depth the Black Caps boast in their seaming stocks.
