De Graaf transitioned to the coxless four event thereafter. He teamed with Freek Robbers, Jan van der Bij and Nelson Ritsema in the final stage of the 2019 World Rowing Cup in Rotterdam, where they placed seventh. In early 2020, national team head coach Mark Emke switched out veteran Vincent van der Want in favor of de Graaf on the Dutch boat. The new crew composed of de Graaf, van der Bij, Ritsema and Boudewijn Röell won the gold medal at the 2020 European Championships in Poznań. They were unable to repeat as European champions in 2021, however, finishing in fourth place. De Graaf competed with the crew the delayed 2020 Summer Olympics in Tokyo, which they had qualified for due to their performance at the 2019 World Championships prior to his inclusion. At the Tokyo Games he helped the crew reach the final via repechage, where they ultimately placed sixth.