2009-10: Patrik Bartosak made his debut in the Czech Extraliga (U20) junior league – appearing in one game for third place HC Vitkovice and handled the bulk of the goaltending for HC Vitkovice's U18 team. In 36 regular season games he had a 1.93 goals against and a league-best .948 save percentage. HC Vitkovice finished first in the U18 junior league. In two playoff games, Bartosak had a 2.77 goals against and .922 save percentage.
2010-11: Bartosak appeared in 37 games for the HC Vitkovice U20 team as a 17-year-old. Playing for the sixth place club he was 25-12 and had 3 shutouts with a 2.75 goals against and .914 save percentage. He stopped 27 of 30 shots in his only playoff game. He also skated in 17 games for HC Vitkovice's U18 team including four playoff games. Bartosak was selected by Red Deer (WHL) in the first round (59th overall) of the 2011 CHL Import Draft.
2011-12: Bartosak appeared in 25 games for the Red Deer Rebels in his first WHL season; suffering a season-ending shoulder injury in January. He finished the season with a record of 14-11 and had 1 shutout with a 2.74 goals against and .915 save percentage. He was invited to the NHL Draft Combine and ranked eighth amongst North American goalies in Central Scouting's final rankings prior to the 2012 NHL Draft.
2012-13: Bartosak proved to be fully recovered from the previous season's shoulder injury, playing in 55 games for the WHL's Red Deer Rebels and representing the Czech Republic at the 2013 U20 World Junior Championship. He had the WHL's fourth-best goals against (2.26) and was 33-14-5 with 5 shutouts and a .935 save percentage. Red Deer finished third in the Central Division and reached the second round in the playoffs. Bartosak was sharp in the playoffs, finishing 5-3 with one overtime loss and had 1 shutout; posting a 1.97 goals against and .941 save percentage. Bartosak appeared in five games for fifth-place Czech Republic at the WJC and was 3-1 with a 2.74 goals against and .896 save percentage. In his second year of draft eligibility, Bartosak was ranked eight amongst North American goalies by Central Scouting in their final rankings prior to the 2013 NHL Draft.
Bartosak moved to North America to play in the WHL, where he played well for the Red Deer Rebels. But a shoulder injury cut short his rookie season, leaving the Czech goaltender as somewhat of a mystery player. Bartosak was among the top goaltenders in the WHL at the time of his injury. Bartosak's style does not fit neatly into any standard goaltending description, but he makes use of his size and some athletic ability to be an effective junior goaltender. It remains to be seen if his game will translate to the pro game, but there is some potential for the big Czech to round into a solid NHL talent.