I swear a #6 is the rarest position in football these days. Every defensive midfielder apart from Rodri needs someone behind him. Joao Neves when he was being discussed as a transfer, Casemiro now needs someone behind him, during the Euro's people saying Rice needed someone to sit behind him. Ugarte, Berge, Fofana, nobody can play as #6.
For what it's worth, I watched Ugarte through-out the Copa America and he played as Uruguay's deepest midfielder. He sat in-front of their defence when they had the ball and looked to mop up anything that leaked from their counter press. The major difference from how Casemiro has played as our #6 the last few years, is he doesn't get involved in the build-up play much at all. Uruguay played very direct. Whenever the ball was played into him, he would bounce it straight back. One of the games I watched, I think against USA, he hardly received the ball from a pass.