He'd never played at a Hearthstone tournament before.
It's often the case in Hearthstone tournaments that experienced players end up winning the grand prizes, like with Tom60229 at the Hearthstone Championship Tour (HCT) World Championships in Amsterdam earlier this year, but the recent HCT Sydney competition was actually won by a total newcomer.
Jack 'Jakattack' Gifford had qualified for the finals of the Sydney stop on the HCT tour, but had never played in a Hearthstone tournament, however, he went on to win the whole thing, lifting the trophy without suffering a defeat and earning himself 15 HCT points (which allow players to qualify for future events) as well as $7,500 USD.
The Blizzard Twitter account for Australia and New Zealand was quick to congratulate the player, who comes from New Zealand and surprised a lot of people with his victory. Did you happen to see him play?