The kid they call Willy simply wouldn't shut up.

The Toronto Maple Leafs teenage wunderkind had learned that his Marlies teammate, Rich Clune, was training with an Olympic boxer and mixed-martial-arts fighter, and he was captivated by the idea.

One of the last players anyone could picture throwing a punch on the ice wanted to do it in the ring, but Clune – who had sat next to William Nylander for months in the AHL – was terrified.

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No way, he said.

"He kept bugging me," Clune said. "He was like 'I want to come' over and over. I said, man, I'm not bringing you to a boxing workout because if you get hurt on my watch, I'm going to get assaulted by [Mike] Babcock and Sheldon Keefe and Kyle Dubas and Lou [Lamoriello]. But also if you somehow the next week punch someone on the ice and get into a fight, I'm going to get in trouble.

"And he kept bugging me. He was biting my ankles every day."

Eventually, Clune relented. Nylander showed up at OpenMat, an elite fighting gym in downtown Toronto, and started learning from a former member of the Spanish Olympic boxing team named Jorge Blanco, one of OpenMat's trainers.

At first, Nylander looked like someone who had never thrown a punch. His stance was bizarre and his technique non-existent.

But, over the course of the next 90 minutes, Clune couldn't believe what he saw. As Nylander followed Blanco's commands, the 5-foot-11 Swedish kid with long blond hair and cherubic good looks began to look like a fighter.

"By the end of the class, he's snapping a right cross effortlessly and with almost perfect technique," Clune said. "Snapping it loud with his hips moving and the body throwing the punch. You could just see the natural athleticism and attention to detail. He was able to put it together."

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A few NHL teams have been caught off guard by Nylander of late. In back-to-back games two weeks ago, he rang up two goals and three assists in consecutive Leafs wins over Buffalo and Calgary, signalling his arrival as a difference maker in a league he is only beginning to get his feet wet in.

Those were his 11th and 12th NHL games, and like the boxing ring, it has taken time for Nylander to adapt. Some nights he has looked overwhelmed and frustrated that he can't pull off the same moves that were working only a month ago in the minors. Other nights, he isn't noticeable at all.

Nylander said he's getting more comfortable in the NHL every day. "You're playing against more skilled players. You've got to be ready for anything. I mean, they're almost like you are. It's a little different from the AHL."

Those who have gotten to know Nylander over his short time in North America have no doubt he will start to make a bigger impact with the Leafs soon.

"Willy has skill," said Babcock, the Leafs coach, who has given Nylander a healthy 16 minutes of ice time a night in his first 16 games heading into Thursday's rematch with the Sabres. "He's a huge talent."

"He can do everything offensively," Leafs veteran centre Tyler Bozak added.

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Taken eighth overall in the 2014 NHL draft, the first under Leafs president Brendan Shanahan, Nylander was called up with much fanfare at the trade deadline. Since his draft day, he has done nothing but pile up points, with 20 in 21 games in Sweden's top league with Modo last year as an 18-year-old and 77 in 74 games with the Marlies over the past two seasons.

That kind of production, as a pro, at that age, is exceedingly rare. The only players that young to produce more than Nylander's nearly point-a-game pace in a season in Sweden were long-time NHLers Tomas Sandstrom and Markus Naslund. And only two players under the age of 20 have ever produced more than 1.2 points a game in as many games as Nylander did this season in the AHL.

What makes him unique has been on display early with the Leafs. When Nylander is effective, he has the puck, which is why the organization has made a big push for him to play at centre. Listed at 190 pounds, he doesn't look big on the ice, but his principal talents aren't about strength. They're his vision and ability to control the play, sometimes by dancing high in the offensive zone – where the defence typically stations – to create openings and confusion among defenders.

From there, he can survey the entire offensive zone, and either find a teammate or fire a shot on net.

"His skill set is special," Keefe, the Marlies' coach, said. "You really see it at this level. He's very patient with the puck. His head's up a lot. He sees a lot of things on the ice that other people don't see. He's one of these unique players that has the ability to play at what can often come across as slow because he's one of those guys that's slowing the game down. He's a unique player in that sense."

"A lot of forwards are best below the top of the circles," defenceman Connor Carrick explained. "He can work with that extra five to 10 feet between the blueline and the top of the circle and create space for himself and keep guys on his hips and cut back and do the things that you're seeing him do. I remember [Red Wings star Pavel] Datsyuk did that a lot when I was growing up. I'm not saying that's the comparison. But he's able to make plays up in those areas and take guys 1-on-1, skate them into areas to create a 2-on-1. That's the idea offensively. I think he does it so naturally."

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"He seems to see the whole ice," added Clune, who compared him to Filip Forsberg, another young Swedish star he played with in Nashville.

Early on, Nylander has proved to be an NHL-level passer and shooter. He plays with two sticks – a Bauer Vapor and a CCM Ultra Tacks – that both have extremely low flex ratings (77 and 75), which makes them bend like a rubber band and whip the puck quickly and with precision.

He has already set up multiple teammates on breakaways or clean chances with remarkable passes thanks to his mastery of that stick.

"He plays in the middle of the ice so he kind of needs a little bit of give," Carrick said. "You can't be really leaning on your stick to try to create the passing lanes because the longer you're leaning on your stick the easier it is for the other guys to read it. They're getting your pass. If he can kind of sling it east and west real quick, it helps him."

"The stick does a lot more of the work for you," Keefe said, noting he has seen a lot of young players on the small side switch to low-flex models.

Off the ice, Nylander is often quiet, especially in his new role as media darling. But teammates describe him as humble and reserved and also a bit of a jokester, someone who will display more personality as he becomes more comfortable. With the Marlies, he quickly grew accustomed to jibes about his flowing locks – which he had to trim when he joined the Leafs to comply with Lamoriello's old-school grooming policy – and learned to come up with his own digs, even to veterans such as Clune.

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In the coming days, Nylander is set to return to the Marlies and lead them into the AHL playoffs, where they are heavily favoured to win the franchise's first Calder Cup. Keefe says he has few doubts he can handle the pressure of being the face of the franchise, with the Marlies and eventually the Leafs.

"He's a young guy finding his way," Keefe said. "There's a lot of attention on him, and he's dealing with a lot. But he doesn't change his attitude or his demeanour. The guys appreciate that."

"He's a driven kid," Clune said. "He works hard in the gym. Likes to train. He's your regular 19-year-old, but he's also a superstar. There's no ego with him, which is cool to see.

"But I think his heart broke when he had to cut his long, blond hair that he was in love with."