2009-10: A.J. Michaelson scored 19 goals with 16 assists and was plus-12 with 4 penalty minutes in 24 games for Minnesota's Apple Valley High School as a sophomore. Apple Valley reached the state tournament after defeating Woodbury in the Section 3AA title game. Michealson had 2 goals with 2 assists in the 4-0 win over Woodbury. Michaelson was selected by Waterloo in the first round (14th overall) of the 2010 USHL Futures Draft.
2010-11: Michaelson skated in seven USHL games for Waterloo after competing in the Midwest High School elite league and Bauer National Invitational tournament prior to his junior season at Apple Valley HS. In his stint with Waterloo, which included one playoff contest, he had 1 assist and was minus-three with 2 penalty minutes. In 23 games of elite league play he scored 11 goals with 13 assists for Team Southeast. He had one goal in three games for Minnesota White, which won the Bauer NIT. Michaelson scored 31 goals with 31 assists and was plus-35 with 8 penalty minutes in 28 games for Apple Valley. Apple Valley lost, 1-0, to Eagan in the Section 3AA Final. Michaelson committed to playing college hockey at Minnesota in 2012-13. Michaelson was selected by Portland in the fifth round (108th overall) of the WHL Bantam Draft.
2011-12: Michaelson opted to play in the USHL with Waterloo rather than playing his senior season at Apple Valley HS. In 53 games for the Black Hawks he scored 6 goals with 14 assists and was minus-one with 8 penalty minutes. Waterloo finished third in the Western Division and reached the Clark Cup playoff finals. In 14 playoff games prior to the decisive fifth game with Green Bay, Michaelson scored 2 goals with 5 assists and was plus-four with 4 penalty minutes. He was ranked 87th amongst North American skaters in Central Scouting's final rankings prior to the 2012 NHL Draft.
2012-13: Michaelson fought to crack the University of Minnesota lineup as a freshman, performing fairly well when given the opportunity. He appeared in 22 games, scoring 3 goals with 3 assists and was +4 with 4 penalty minutes. The Gophers were one of the top teams in the country, finishing second in the WCHA. Minnesota lost to Colorado College in the WCHA tournament semifinals and were beaten by eventual national champion Yale, 3-2, in overtime in an NCAA West Regional semifinal game.
Michaelson has been a fairly promising prospect who seems to be going backwards in his development. His offensive game is not developing even at the junior level, and his defensive game is only slightly better at this stage. Michaelson is a good skater with decent size, so improvement in other areas of his game could help to draw some attention from the pro teams, but he appears to be a long way from being a pro at this time.