 A standout in junior with the Calgary Hitmen of the WHL, Alzner won two World Junior Hockey Championship gold medals with Team Canada 2007 and 2008 (as the captain).Alzner was named the Western Hockey League (WHL)'s top player and Canadian Hockey League (CHL)'s top defenceman in 2008.He won back to back Calder Cups and won the Presidents' Trophy in 2016 and 2017 with the Washington Capitals.