2006-07: Playing as a rookie with the Ice Dogs, Alex Pietrangelo certainly made an impact. Playing in 59 games, Pietrangelo finished in the top 10 amongst OHL rookies in points with 52 (seven goals, 45 assists). He was also in the top 15 in points among OHL defenseman. He led all Ice Dog defenseman and rookies in goals, assists, points and plus/minus with a +40. Despite his stellar regular season, Pietrangelo struggled in the playoffs. In four games, Pietrangelo failed to record a point and had a plus/minus of -7.
2007-08: Pietrangelo became one of the top defensive prospects in the OHL. He was a participant in the Canada-Russia Summit Series, was ranked fifth overall, and the third highest ranked defenseman by NHL Central Scouting. Pietrangelo eclipsed his goal total from last season and improved on his point total and plus/minus. His strong play was rewarded by being named to the Eastern Conference All-Star squad at the OHL All-Star Classic.
2008-09: Pietrangelo skated in 8 games with St. Louis, recording 1 assist and 2 PIMs before being assigned to his junior team in Niagara. He scored 8 goals, 21 assists for 29 points in 36 regular season games for the IceDogs. In 12 playoff appearances, the blueliner notched 1 goal, 5 assists. He finished the season with the Peoria Rivermen in the AHL, appearing in 1 regular season game before recording 3 assists in 7 playoff games. Pietrangelo played in his first WJC, scoring 1 goal, 2 assists in 6 games as Canada captured the gold medal.
2009-10: Pietrangelo stuck with the Blues into November, but only appeared in 9 games to allow his entry-level contract to slide another year. He notched 1 goal, 1 assist in that early season look with St. Louis before joining Canada's U20 WJC camp. Although Canada finished with the silver medal, Pietrangelo himself enjoyed a stellar tournament with 3 goals, 9 assists for 12 points in 6 games. He was named the tournament's Best Defenseman after leading his position in goals, assists, and points. He was also named one of Canada's top three players by the coaches after serving as one of the alternate captains. After the tournament, Pietrangelo was promptly traded from Niagara to Barrie in the OHL. He scored 9 goals, 20 assists for 29 points in 25 games for the Colts to finish the season, following that up with 2 goals, 12 assists for 14 points in 17 playoff games.
Pietrangelo possesses a big 6'3 frame. He mixes his size advantage with a strong skill set that makes him a dangerous defenseman. Pietrangelo has excellent on-ice vision and a high hockey IQ. His offensive upside is tremendous, with his shot, mobility, and creativity with the puck. Very successfully can quarterback a power play. Additionally, he is solid in his own end, with good positioning, and excellent defensive instincts.