2009-10: Gaunce led all of Ontario midget AAA in scoring playing for the Markham Waxers. In 86 games he scored 55 goals with 93 assists. Gaunce was selected by the Belleville Bulls in the 1st round (2nd overall) of the 2010 OHL Priority Draft.
2010-11: Gaunce skated in 65 games for Belleville as an OHL rookie and represented Ontario in the 2011 U17 World Hockey Challenge. He scored 11 goals with 25 assists and had 40 penalty minutes. Gaunce was minus-31 on a Belleville team that won just 21 games and gave up 97 more goals than it scored. In the Bulls four-game first-round series with Mississauga St. Michael's he was minus-3 with 4 penalty minutes. Gaunce scored 2 goals with 1 assist and had 18 penalty minutes in five games for Ontario at the WHC.
2011-12: Gaunce was the leading scorer for Belleville in his second season and represented Canada at the 2012 U18 World Junior Championship. In 68 games he scored 28 goals with 40 assists and was plus-4 with 68 penalty minutes. Belleville was much-improved; finishing second behind the Ottawa 67's in the East Division. In the playoff series with Ottawa he skated in all six games and was minus-2 with 1 goal and 2 assists. . Gaunce scored 3 goals with 1 assist and was plus-4 with 8 penalty minutes in seven games for bronze-medal winning Canada at the U18 WJC. Gaunce was ranked 13th amongst North American skaters in Central Scouting's final rankings prior to the 2012 NHL Draft.
If Gaunce were a better skater, he would be considered top-6 material. As it stands, his attention to the defensive side of the game and ability on face-offs makes him a definite candidate for role as a third-line checking center. Gaunce has the size to battle with most players but doesn't always have the speed to keep up. But he'll pay attention to the defensive zone and win most of the puck battles along the boards, making him a potentially valuable player when a team is looking to preserve a lead.