2008-09: Demelo played 74 games for the London Junior Knights midget minor team in Ontario. He scored 11 goals with 34 assists and had 46 PMs. He was selected by Mississauga St. Michael's in the 2nd round (34th overall) of the 2009 OHL Priority Draft.
2009-10: Demelo skated in 20 games for Mississauga St. Michael's in the OHL – spending most of the season with the Junior A Mississauga Chargers. He had 1 assist and was +3 with 12 PMs in limited ice time with the Majors. In 36 games for the Chargers he scored 9 goals with 20 assists and had 24 PMs.
2010-11: Demelo played in 67 of 68 games as Mississauga St. Michael's dominated the regular season in the OHL – winning 53 games. Demelo was +31 and scored 3 goals with 24 assists and 70 PMs. The Majors faced Owen Sound in an epic OHL final series, won by Owen Sound in overtime of the seventh game. Demelo was +10 in the playoffs with 1 goal, 4 assists and 15 PMs in 20 games. The Majors hosted the Memorial Cup and in five games during the tournament Demelo was scoreless with 4 PMs. Ranked 121st amongst North American skaters in Central Scouting's final rankings, he was selected by San Jose in the sixth round (179th overall) of the 2011 NHL Draft.
2011-12: DeMelo improved on his offensive numbers of last season for a much weaker Mississauga team while playing on both specialty units and big shutdown minutes. The defender scored seven goals (four on the power play and one shorthanded) along with 40 assists and a good plus nine rating while taking 70 PIMs in 67 games. DeMelo and the Mississauga St. Michael's Majors lost a very tight, physical first round OHL Playoff series 4-2 against the Barrie Colts. The physical offensive defender was only able to contribute a power play goal along with an assists and a minus three rating while taking 13 PIMs (one fighting major) in the series. The Shark were impressed enough to give the young defenseman an ATO to play for AHL Worchester for four games to end his year. He was a solid plus three rating with an assist in the four AHL games and the team signed to a three year NHL entry level contract.
DeMelo is a mobile, puck moving defenseman who likes to jump up into the play as the trailer in the offensive zone. The big defender plays a good two-way game, has good hockey sense and can play on both specialty units. He will need to add more muscle mass, up his offensive play and bring more physicality down low in his own end of the rink in order to play at the NHL level.
DeMelo has another year at the junior level in the OHL for Mississauga to get bigger and continue improving his overall game. He will be expected to bring leadership, character and more offense to his team.