Participating countries were asked to declare three players last month, and Armstrong said the choices for Hockey Canada were straightforward. The names were sent to the Canadian Olympic Committee, which subsequently forwarded them to the International Olympic Committee.
"It goes without saying that Sid is Sid, Connor is Connor, and Alex has got a wealth of experience from the [2014 Sochi Olympics] team to the [World Cup of Hockey 2016] team to the captain of a Stanley Cup champion (St. Louis Blues in 2019)," Armstrong said Friday. "Those guys are at the top of their game in the League too, and they're proven winners."
Crosby, captain of the Pittsburgh Penguins, provided one of hockey's most memorable moments when he scored in overtime of the gold medal game to give Canada a 3-2 victory against the United States at the 2010 Vancouver Olympics. The 34-year-old center was Canada's captain at Sochi and the World Cup, each won by Canada.
Armstrong said he's had numerous conversations with Crosby to date and called him "our team leader."
"I've talked to Sid more than any (player) just because of my past relationship with him, and he'll be our leader," he said. "We go back to the 2010 Olympics. I wouldn't call us best friends, but I feel comfortable calling him on the phone, and he feels comfortable picking it up.
"He'll lead our team. He'll be a great help to the coaching staff by delivering their message to the rest of the players. To me, he's just Sidney Crosby. He's the best player on the planet for more than a decade. I don't think the rest of the players will be in awe of him because you don't get to be an Olympian by being in awe of other players. But they'll respect him, just like his teammates did when he wore the captain's 'C' at the 2014 Olympics, the 2016 World Cup, and the same way he respected Scott Niedermayer, our captain, at the 2010 Olympics."
This will be the first Olympics for McDavid, a 24-year-old center who is captain of the Edmonton Oilers. Armstrong said he's been introduced to McDavid and has spoken to him several times.
"It's a tremendous honor and to be named with those two, it's elite company," McDavid said Tuesday. "I feel very humbled and excited for that opportunity."
Pietrangelo, a 31-year-old defenseman, played his first 12 NHL seasons with the Blues, including as captain for the final four, before signing a seven-year contract with the Vegas Golden Knights on Oct. 12, 2020.
"I've been fortunate that my relationship with Alex goes back a while," said Armstrong, who has been St. Louis general manager since July 1, 2010.
Armstrong was part of Canada's management group for the Olympics in 2002 (Salt Lake City), 2010 and 2014. He was named GM of Canada on Feb. 3.
Canada's management and coaching staff held meetings last month in Banff, Alberta, where the decision was made to list Crosby, McDavid and Pietrangelo. The next task is to submit a list of 55 players who will be candidates for the Olympic team Oct. 15.
NHL.com independent correspondent Derek Van Diest contributed to this report