They weren't when several teams inquired about the No. 3 pick in the 2017 NHL Draft that the Stars ultimately used to select Heiskanen, and they weren't when the Ottawa Senators were shopping two-time Norris Trophy winner Erik Karlsson last offseason.
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"On each occasion, the reply was an easy one," general manager Jim Nill told NHL.com on Sunday. "It was a simple 'no.'
"We knew right from the start. Whenever I was talking about any trades, Heiskanen was not going to be involved no matter who I was talking to."
If the best trades are the ones you don't make, credit Nill for being bang on with these decisions.
"We knew we had a pretty special player," said Nill, who said he has lost count of how many times Heiskanen has come up in trade talks. "Now you're never sure how quickly the potential is going to come to fruition, but we knew he'd be good."
He's been all that and more.
Heiskanen's first-period goal helped the Stars defeat the St. Louis Blues 4-2 in Game 2 of the Western Conference Second Round on Saturday. The best-of-7 series is tied 1-1 heading into Game 3 at Dallas on Monday (8 p.m. ET; NBCSN, TVAS, SN).
Heiskanen was informed after the victory that he was not one of the three finalists for the Calder Trophy, which is awarded to the NHL rookie of the year.
Getting the nod instead were Blues goalie Jordan Binnington (24-5-1, 1.89 goals-against average, .927 save percentage), who allowed Heiskanen's Game 2 goal; Buffalo Sabres defenseman Rasmus Dahlin (nine goals, 35 assists in 82 games); and Vancouver Canucks forward Elias Pettersson, who led NHL rookies and the Canucks in goals (28), assists (38) and points (66).
Heiskanen handled the news with class and a shrug of his scrawny shoulders, an attitude he maintained Sunday.
"Those three guys, they're good players," Heiskanen said. "I don't think about it. Of course, it would be nice to be part of it. But I can live with it. Not that big a thing."
Video: DAL@STL, Gm2: Heiskanen pots Hintz's gorgeous pass
What is a big thing, Heiskanen said, is the faith that Nill and the Stars have in him.
He admitted being aware of the Karlsson trade rumors, but he said he didn't worry about them. The Stars had always told him how much they believed in him. By rejecting the offers of other teams, they proved that.
"I saw some news, some discussions about that stuff," Heiskanen said. "I didn't think about it too much. I just went about doing my things. I'm lucky that they trust me on the ice. It feels good.
"It's an unbelievable feeling about how much they back me."
Nill recalled being at the Stars table for the 2017 draft, when the New Jersey Devils and Philadelphia Flyers held the first two picks. Forwards Nico Hischier and Nolan Patrick were rated as the top two prospects, but Nill knew Heiskanen would be in play if either team chose to pick a defenseman instead.
They didn't, and Nill is glad it played out that way.
"We had No. 3 overall that year, and I had mentioned to people I was open to trades and stuff," he said. "There was a lot of interest there for that pick. You don't know if he's going to go 1, 2, 3, 4, 5, but in the end, he's a guy our franchise needed, and he's a guy we needed to be the guy."
For Nill, Heiskanen is Calder-worthy even if he wasn't named a finalist.
"The three guys who were nominated, I think they all deserve to be there," Nill said. "I just think where we're located, we're not seen a lot up on the East Coast or up in Canada, but I think people will watch him in the [Stanley Cup] Playoffs and think, 'Maybe he should be there.' I know there will be a lot of accolades for him down the road.
"He'll shrug it off, but he'll use it as motivation."
Nill marveled at the maturity of Heiskanen, who won't turn 20 until July 18.
After being drafted by the Stars, Heiskanen spent the 2017-18 season with HIFK of the Finnish Elite League and had 23 points (11 goals, 12 assists) in 23 games. He represented Finland at the 2018 IIHF World Championship last May and provided Nill with an indication that he was NHL-ready.
"His first game was against Canada and on the opening face-off, Connor McDavid just blew by him," Nill said. "I remember thinking 'uh oh.' But it didn't happen again. He knew what he'd done wrong and made the adjustment. I just told myself, 'This kid gets it.'"
In more ways than one.
The Stars, confident that Heiskanen could play in the NHL this season, brought him to Dallas three months later to get acclimated to life in North America. On the agenda: getting a driver's license and finding a place to live.
"He's an amazing story," Nill said. "Usually when you bring a teenager in, especially from Europe, you have to hold his hand a bit. Not him. From Day One, he told us, 'Don't worry, I've got this.' And he's been like that ever since."
Heiskanen had 33 points (12 goals, 21 assists) during the regular season and has three (two goals, one assists) in eight playoff games. More impressive has been his ice time. He's averaging 25:48, second on the Stars in the playoffs and up from 23:07 during the regular season.
"I feel good," he said. "Playoff pressure? What pressure? This is fun."