Armstrong was rounding the bases during the WBC qualifying round in September when he ruptured an Achilles tendon. After he was helped off the field, Armstrong refused to leave the dugout as Canada went on to beat Germany 16-7.
Canada cruised through qualifying to return to the international tournament and Armstrong went home to rehab.
"It's one of those things where I'm not sure even had I been named to the team health-wise I would have been able to compete at this point," said Armstrong, who lives in Arizona and visited his former teammates to show some support.
"Disappointing is not the word I would use. It's something I would have loved to have been a part of. But in all reality, more in my heart is them doing well and getting onto the second round and hopefully doing a run at this thing."
The affable catcher from Surrey, B.C., is part of a core group of players that have come up through the Baseball Canada system. Armstrong was on the team that beat the United States to win gold at the Pan American Games in 2011, a matchup he and several of his teammate say was the biggest game of their careers.
"(Armstrong's) been part of the program forever," said teammate Tim Smith. "It was just too bad what happened to him in the tournament there. It's a tight-knit family. Guys, more than just him, other guys have come out too just to show their support anyway possible. It's appreciated. We're pulling for gold."
There are 10 players at the WBC who competed at the Pan Am Games in Mexico. They are often overlooked when playing in the shadow of major-leaguers such as Joey Votto and Justin Morneau, but together they form the backbone of Canada's international teams.
National team director Greg Hamilton says players such as Smith, Jimmy Van Ostrand, Andrew Albers and Jonathan Malo earned their rosters spots with the Pan Am gold medal, Canada's first at the event.
"You respect success," said Hamilton. "You respect those that have success and find a way to achieve, and that group was a special group. ... That's why you take note of that when you have a need and you give them the opportunity to potentially impact a roster at a level that may be beyond where they've got to in their professional careers to date. But they've shown that they're capable of really having an impact."
Longtime Canadian manager Ernie Whitt can't help but smile when he thinks about winning gold.
"I still see the kids out there crying. It was like their World Series, because we had never accomplished that, and that will always be etched in my mind," he said. "More than any losses, I will always look at that win, more than anything.
"It was like, finally. Finally."
Van Ostrand, who drove in the two runs that won gold for Canada, is the player Armstrong says the team has come to rely on in the clutch.
Van Ostrand left his first spring training with the Washington Nationals to join the WBC squad. The first baseman from Richmond, B.C., began his international career with Canada at the 2007 World Cup, and had four home runs and 10 RBIs during WBC qualifying.
He says there remains a bond between the players that provided Canadian baseball with an international breakthrough in 2011.
"When it happened you're so caught up in the moment and focus on competing and trying to get a win. Things like that," said Van Ostrand, who is expected to share some WBC time at third base with Taylor Green following Brett Lawrie's injury.
"Now that it's had a little time to sink in a little bit, you watch the replay or you get back with these guys, some of the guys that were there for it, and reminisce a little bit. It's definitely pretty special."
Baseball Canada is hoping that success translates into a run at the WBC. As for Armstrong, who is nearing the end of his rehab and will join an independent team in April, he hopes baseball fans take notice of the players that helped get Canada back to the tournament.
"I mean for them to be out here on this stage now, it's something that I really hope there's a big moment where one of them get to do something the whole country takes notice of," he said. "Because they're out there doing it for all of us that came up through the system and that kind of thing.
"I really hope that one of them get that opportunity."