2009-10: Maidens scored 63 goals with 41 assists in 57 games for the Hamilton Junior Bulldogs midget minor team. He was selected by Owen Sound in the first round (4th overall) of the 2010 OHL Priority Draft.
2010-11: Maidens had an up-and-down season in his first year with Owen Sound but scored the biggest goal of the season – an overtime game-winner – in Game Seven of the OHL championship series with Mississauga St. Michael's. In the regular season, a nagging hip injury limited him to 47 games. He scored 10 goals with 11 assists and was plus-four with 11 penalty minutes. In 22 playoff games he scored 6 goals with 4 assists and was plus-seven with 13 penalty minutes. Maidens skated in all four games for Owen Sound at the Memorial Cup and was minus-one with 1 goal. He was selected to play for Ontario at the U17 World Hockey Challenge but missed the tournament due to his hip problems.
2011-12: Maidens was expected to be a key returnee for the defending OHL champion Attack in his second season but was limited to 28 games and missed the entire playoffs due to concussion-like symptoms. He scored 12 goals with 11 assists and was minus-two with 4 penalty minutes but did not play a game after November 30th. Maidens was invited to the NHL Draft Combine and ranked 35th amongst North American skaters in Central Scouting's final rankings prior to the 2012 NHL Draft.
There isn't much question about the talent level of Maidens. He is a hard-working forward with good size who also possesses some offensive ability. The problem is that Maidens suffered what was thought to be a season-ending concussion in 2011-12 that ended his season after 28 games. The severity of his injury could leave Maidens vulnerable to more concussions that could inevitably cut short his hockey career. The Senators have taken the risk in drafting Maidens, but they might be rewarded if he can stay healthy.