Answer
Frenkie de Jong joined Ajax in 2016. He was signed from Willem II, where he had played since 2014. De Jong quickly became a key player for Ajax, helping the team win the Eredivisie title in 2018-19. He also played a major role in Ajax's run to the semi-finals of the UEFA Champions League in 2018-19. In 2019, De Jong joined Barcelona for a fee of €75 million.