The central midfielder is the team’s connector. He receives from the CDM, rotates with the 10 and links wingers and strikers.
Styles vary: the deep-lying playmaker sprays passes from next to the number 6, the creative 8 breaks between the lines, and the box-to-box 8 covers more vertical distance than anyone.
A modern midfield often has two 8s with complementary profiles — one more defensive, one more attacking — next to a single 6.