There are different types of #6 in football
- The screening and sliding midfielder
- The libero
- Regista
- Deep Playmakers

The screening and sliding midfielder

- Kanté, Kovacic

A screening midfielder usually sits in front of the central defenders and his job is to anticipate transition and win the ball back.

The libero

- Matic, Declan Rice

A libero is a midfielder who drops into the defence line, allowing the two central defenders liberty to split wide so that the fullbacks can push high. A libero is usually a physical defensive midfielder who is good in the air and good 1v1

A Regista

- Pirlo, Jorginho, Gilmour

A regista is a midfielder who is good at controlling the tempo of the game. The role of a Regista is to recieve the ball from the defenders and help progress it forward. It requires the ability to find quick passes in tight spaces.

A Deep Playmaker

- Pirlo, Fabregas, Gilmour

A deep playmaker is usually asked to do everything a Regista does but also to find through balls and long balls throughout the game more than a Regista.

Irrespective of the role, a #6 needs to possess ability to win the ball back and ability to find passes in all sorts of situations; ie., Under pressure, tight spaces, and creative long balls.

Declan Rice is the kind of midfielder Lampard would fancy. A libero allows both fullbacks to push high, something Lampard likes. We are yet to see Reece James and Alonso/Emerson start a game together. Someone like Rice can help us do that.

However personally, I don't think Rice justifies his price tag. He is good on his good days, but he is often caught napping ( If you know, you know ), not putting in enough energy.