De Young is a midfielder. In 2002, he played for the St Andrew's club after not having played for the club in two years. He was the first player from St Andrew's to make Australia's senior national team. In 2010, he played in the final game of the season for his state team in the Australian Hockey League.
He won a gold medal at the 2004 Summer Olympics, Australia's first ever gold medal in men's field hockey at the Olympics. His mother, father and two brothers were in Athens to watch him win gold.
In 2006, he represented Australia at the Azlan Shah tournament in Malaysia. He competed in the 2007 Champions Trophy competition for Australia.
New national team coach Ric Charlesworth named him, a returning member, and fourteen total new players who had few than 10 national team caps to the squad before in April 2009 in a bid to ready the team for the 2010 Commonwealth Games. In 2009, he was a member of the national team during a five-game test series in Kuala Lumpur, Malaysia against Malaysia. He was a member of the national team in 2010. That year, he was a member of the team that finished first at the Hockey Champions Trophy. In May 2011, he played in the Azlan Shah Cup for Australia. The Cup featured teams from Pakistan, Malaysia, India, South Korea, Britain and New Zealand. In December 2011, he was named as one of twenty-eight players to be on the 2012 Summer OlympicsAustralian men's national training squad. This squad was narrowed in June 2012. He trained with the team from 18 January to mid-March in Perth, Western Australia. In February during the training camp, he played in a four nations test series with the teams being the Kookaburras, Australia A Squad, the Netherlands and Argentina. He played for the Australian A team in their 3-1 loss to the Kookaburras in the first round of the competition. He scored his team's only goal. He was selected to play for Australia at the 2012 Summer Olympics, where they won the bronze medal.