And Verhaeren sees striking similarities between the swimmer dubbed 'The Flying Dutchman' and Australia's Big Tuna.
"Kyle is a lot stronger than the Pieter that I coached, more physical strength, has also a bit more anaerobic skills," said Verhaeren.
"But aerobically, he is actually of the same make-up as Pieter was. So that means that he can actually combine the 100 and 200."
Chalmers, at the Australian titles in Adelaide this week, won his favoured 100m freestyle.
The 20-year-old set a fresh Commonwealth record doing so, bettering the time that delivered him Olympic gold in the event in 2016.
Chalmers then collected the national 200m freestyle title, evidencing the 100-200 golden goal at next year's Olympics is truly on track.
Which is where the Belgian professor comes in.
Professor Jan Olbrecht has crafted specific testing to determine VO2 Max levels – in layman's terms, the amount of oxygen a person can utilise during intense exercise.
"It gets very technical, VO2 max which is oxygen uptake and lactate production," Verhaeren said.
"And the professor has a unique system in the world to simulate that and to give training advice to a coach.
"He is not saying 'you have to train like this'. He's more explaining 'this is the type of athlete you have and these are the training actions'."
Verhaeren shares the professor's information with Verhaeren, who in turn relays it to Chalmers' personal coach, Peter Bishop.
"My first Olympics was '96 and ever since, I have worked with the professor," Verhaeren said.
"And Bish adopted this two or three years ago, to start working a little bit in that philosophy and training style and using these tests. It's not the be-all, end-all, but it's a determiner of where your athletes are at and what you could do best in a certain training phase.
"Every coach is different. It doesn't mean that Bish does exactly what I did in the past … but it's good to share knowledge on that level."
Verhaeren is adamant that Chalmers can only improve.
"He is still improving on his skills, he's improving really well on his underwaters, his physique, the testing – it looks very good," he said. "So there is definitely room to grow for him."
But like with van den Hoodenband in 2000, there is a fine line to tread with Chalmers' program.
Chalmers will swim the 200m free, and relay legs, at the world championships this July and next year's Olympics – before he even gets to his pet 100m event.
"It's a lot," Verhaeren said. "And this has always been the delicate balance with someone like Pieter as well."
In Sydney, Van den Hoogenband also contested the 50m freestyle (he won bronze), 4x100m and 4x200m freestyle relays, and medley relays.
"It's a massive program and that is what Kyle is facing as well," Verhaeren said.
He believed Chalmers could also add the 50m dash to his program in the future, but for now it's about finding the training balance between the necessary speed for the 100m and the endurance required in the 200m.
And also brushing up his technical skills – Chalmers himself admitted at the nationals he wasn't yet world-class in such areas.
"He is swimming fast but he's still not polished," Verhaeren said. "He can improve on a few skills. He can improve a little bit on the way he swims it, so stroke rate, keeping the race nice and tidy.
"At the end of the day, what is his greatest gift is he is an incredible racer with an incredible mindset – he refuses to lose. And to combine that fine-tuning process, that polishing, with this incredible race attitude, that is what makes him so good."