2005-06: In John Armstrong’s second OHL season with the Plymouth Whalers, he scored 37 points (14G, 23A) in 65 games. He did not have the best numbers defensively as he would finish the year at a disappointing -19. Armstrong would also participate in the years CHL/NHL Top Prospects game. The Flames must have liked what they saw, because they selected him 87th overall in the 2006 NHL Draft.
2006-07: The center split the season between Plymouth and Peterborough (OHL) for his third year in the league. In 34 games with the Whalers, he tallied eight goals and 21 points, adding another 24 points (11g+13a) in 27 games with the Petes.
2007-08: In his final OHL season, Armstrong tallied 21 goals and 57 points through 65 games with the Peterborough Petes (OHL), his second, and final, season with the club.
2008-09: The QC Flames (AHL) gained a center in Armstrong this season, his first year as a professional hockey player. In 68 games, he scored five goals and 20 points in 68 games, racking up 72 penalty minutes along the way.