Great Britain's Olympic champion Giles Scott said finishing fourth in the Finn Gold Cup was a "wake-up call".
The Rio 2016 gold medallist, 32, was out of contention going into the final race in Melbourne and finished eighth in the double-points event.
"It's frustrating to finish fourth, I wasn't consistent enough," said Scott.
New Zealand's Josh Junior won gold, Dutchman Nicholas Heiner finished second overall and Zsombor Berecz of Hungary was third.
Junior, who only had to finish in the top seven in the last race in Australia, became the first New Zealander to win the event.
Scott, who won the European title in May, added: "It was tough racing, and unfortunately for me it wasn't the way I wanted to end the regatta.
"It would definitely have been nice to have finished this year as European and world champion. But, ultimately, it's not about world titles, it's about preparation for the [Tokyo 2020 Olympic] Games."
Fellow Britons Ed Wright and Henry Wetherell finished 13th and 24th respectively.