"For me, it was trying to bring something different to the game rather than trying to do the same sort of thing," Wagner told Newstalk ZB.
"We have two of the best swing bowlers in the world with Tim and Trent - to try and do the same thing they do, it's just not going to work. I had to find a different way to complement them."
Wagner can remember a moment which saw him completely embrace his new role.
"It wasn't until we were playing a day where the weather was pretty tough, it was quite windy and hard to hit a length, the ball wasn't swinging.
"Myself and Baz [Brendon McCullum] spoke about it, and Baz was a mastermind - [we had] a brilliantly planned field set for me to just bang away, and it took off, and from there on in, with my experience and the amount of times we played, you learn what works and what doesn't. Eventually the plan fell into place."
It's a plan which has paid huge dividends for the South African-born seamer.
In his first two years of test cricket, Wagner's bowling average was 37.9, and he played just six tests in the two years that followed. However, since 2016, Wagner has taken 77 wickets - the third most of any test seamer in that timeframe - at an average of 23.1.
Of course, Wagner's approach doesn't work every time. The West Indies found success attacking the short ball earlier this month, but Wagner is happy to take risks to get rewards.
"At times you know that players are going to take you on and it's going to create opportunities as well, so you might go for a couple of runs but sometimes you prefer to [concede] those runs to break a partnership.
There may not be many opportunities for his tactics to be put into action in the near future. New Zealand's test schedule is minimalist over the next few summers, and Wagner is not in the selectors' short-form plans.
So, until England visit in March, Wagner is back to domestic cricket with Otago, and hoping to do enough to one day become an option in more than test matches.